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SQL Interview Questions with Answers http://www.sqlauthority.com What is RDBMS?

Relational Data Base Management Systems (RDBMS) are database management systems that maintain data records and indices in tables. Relationships may be created and maintained across and among the data and tables. In a relational database, relationships betwee between n data items are expressed by means of  tables. Interdependencies Interdependencies among these tables are expressed by data values rather than by pointers. This allows a high degree of data independence. An RDBMS has the capability to recombine the data items from different files, providing powerful tools for data usage. What is normalizatio normalization? n?

Database normalization is a data design and organization process applied to data structure structures s based on rules that help build relational databases. In relational database design, the process of organizing data to minimize redundancy. Normalization usually involves dividing a database into two or more tables and defining relationships relationships between the tables. The objective is to isolate data so that additions, deletions, and modifications of a field can be made in just one table and then propagated through the rest of the database via the defined relationsh relationships. ips. What are different normalization forms?

1NF: Eliminate Repeating Groups Make a separate table for each set of related attributes, and give each table a primary key. Each field contains at most one value from its attribute domain. 2NF: Eliminate Redundant Data If an attribute depends on only part of a multi-valued key, remove it to a separate table. 3NF: Eliminate Columns Not Dependent On Key If attributes do not contribute to a description of the key, remove them to a separate table. All attributes must be directly dependent on the primary key BCNF: Boyce-Codd Normal Form If there are non-trivial dependencies between candidate key attributes, separate them out into i nto distinct tables. 4NF: Isolate Independent Independent Multiple Relationships No table may contain two or more 1:n or n:m relationships that are not directly related. 5NF: Isolate Semantically Related Multiple Relationships There may be practical constrains on information that justify separating logically related many-to-many relationships. ONF: Optimal Normal Form A model limited to only simple (elemental) facts, as expressed in Object Role Model notation notation.. DKNF: Domain-Key Normal Form A model free from all modification anomalies. Remember, these normalization normalization guidelines are cumulative. For a database to be in 3NF, iitt must first fulfill all the criteria of a 2NF and 1NF database. What is Stored Procedure?

A stored procedure is a named group of SQL statements that have been previously created and stored in the server database. Stored procedures accept input parameters so that a single procedur procedure e can be used over the network by several clients using different input data. And when the procedure is modified, all clients automatically get the new version. Stored procedures reduce network traffic and improve performance. Stored procedures can be used to help ensure the integrity of the database. e.g. sp_helpdb, sp_renamedb, sp_depends etc. What is Trigger?

A trigger is a SQL procedure that initiates an action when an event (INSERT, DELETE or UPDATE) occurs. Triggers are stored in and managed by the DBMS.Triggers are used to maintain the referential integrity of data by changing the data in a systematic fashion. A trigger cannot be called or executed; the DBMS automatically fires the trigger as a result of a data modification to the associated table. Triggers can be viewed as similar to stored procedures in that both consist of procedural logic that is stored at the database level. Stored procedures, however however,, are not event-drive and are not attached to a specific table as triggers are. Stored procedures are explicitly executed by invoking a CALL to the procedure procedur e while triggers are implicitly executed. In addition, triggers can also al so execute stored procedures. Nested Trigger: A trigger can also contain INSERT, UPDATE and DELETE logic within itself, so when the trigger is fired because of data modification it can also cause another data modification, thereby firing another trigger. A trigger that contains data modification logic within itself is called a nested trigger.


What is View?

A simple view can be thought of as a subset of a table. It can be used for retrieving data, as well as updating or deleting rows. Rows updated or deleted in the view are updated or deleted in the table the view was created with. It should also be noted that as data in the original table changes, so does data in the view, as views are the way to look at part of the original table. The results of using a view are not permanently stored in the database. The data accessed through a view is actually constructed using standard T-SQL select command and can come from one to many different base tables or even other views. What is Index?

An index is a physical structure containing pointers to the data. Indices are created in an existing table to locate rows more quickly and efficiently. It is possible to create an index on one or more columns of  a table, and each index is given a name. The users cannot see the indexes, they are just used to speed up queries. Effective indexes are one of the best ways to improve performance in a database application. A table scan happens when there is no index available to help a query. In a table scan SQL Server examines every every row in the table to satisfy the query results. Table scans are sometimes unavoidable,, but on large tables, scans have a terrific impact on performance. unavoidable Clustered indexes indexes define the physical sorting of a database table’s rows in the storage media. For this reason, each database table may have only one clustered index. Non-clustered Non-cluste red indexes are created outside of the database table and contain a sorted list of references to the table itself. What is the difference between clustered and a non-clustered index?

A clustered index is a special type of index that reorders the way records in the table are physically stored. Therefore table can have only one clustered index. The leaf nodes of a clustered index contain the data pages. A nonclustered index is a special type of index in which the logical order of the index i ndex does not match the physical stored order of the rows on disk. The leaf node of a nonclustered index does not consist of  the data pages. Instead, the leaf nodes contain index rows. What are the different index configurations a table can have?

A table can have one of the following index configurations: No indexes A clustered index A clustered index and many nonclustered indexes A nonclustered index Many nonclustered indexes What is cursors?

Cursor is a database object used by applications to manipulate data in a set on a row-by-row basis, instead of the typical SQL commands that operate on all the rows in the set at one time. In order to work with a cursor we need to perform some steps in the following order: Declare cursor Open cursor Fetch row from the cursor Process fetched row Close cursor Deallocate cursor What is the use of DBCC commands?

DBCC stands for database consistency checker. We use these commands to check the consistency of  the databases, i.e., maintenance maintenance,, validation task and status checks. E.g. DBCC CHECKDB - Ensures that tables in the db and the indexes are correctly linked. DBCC CHECKALLOC CHECKALLOC - To check that all pages in a db are correctly allocated. DBCC CHECKFILEGROUP - Checks all tables file group for any damage. What is a Linked Server?

Linked Servers is a concept in SQL Server by which we can add other SQL Server to a Group and query both the SQL Server dbs using T-SQL Statements. With a linked server, you can create very clean, easy to follow, SQL statements that allow remote data to be retrieved, joined and combined with local data. Storped Procedure sp_addlinkedserver, sp_addlinkedsrvlogin will be used add new Linked Server. What is Collation?

Collation refers to a set of rules that determine how data is sorted and compared. Character data is sorted using rules that define the correct character sequenc sequence, e, with options for specifying casesensitivity, casesensitivity,


accent marks, kana character types and character width. What are different type of Collation Sensitivity?

Case sensitivity A and a, B and b, etc. Accent sensitivity a and á, o and ó, etc. Kana Sensitivity When Japanese kana characters Hiragana Hiragana and Katakana are treated differently, it is called Kana sensitive. Width sensitivity When a single-byte character (half-width) and the same character when represented as a double-byte character (full-width) (full-width) are treated differently then it is width sensitive. What's the difference between a primary key and a unique key?

Both primary key and unique enforce uniqueness of the column on which they are defined. But by default primary key creates a clustered index on the column, where are unique creates a nonclustered nonclustered index by default. Another major difference is that, primary key doesn't allow NULLs, but unique key allows one NULL only. How to implement one-to-one, one-to-many and many-to-many relationships while designing tables? One-to-One One-to-O ne relationship can be implemented as a single table and rarely as two tables with primary and foreign key relationships. One-to-Many One-to-M any relationships are implemented by splitting the data into two tables with primary key and foreign key relationships. Many-to-Many Many-toMany relationships are implemented using a junction table with the keys from both the tables forming the composite primary key of the junction table. What is a NOLOCK?

Using the NOLOCK query optimiser hint is generally considered good practice in order to improve concurrency on a busy system. When the NOLOCK hint is included in a SELECT statement, no locks are taken when data is read. The result is a Dirty Read, which means that another process could be updating the data at the exact time you are reading it. There are no guarantees that your query will retrieve the most recent data. The advantage to performance is that your reading of data will not block updates from taking place, and updates will not block your reading of data. SELECT statements take Shared (Read) locks. This means that multiple SELECT statements are allowed simultaneous access, but other processes are blocked from modifying the data. The updates will queue until all the reads have completed, and reads requested after the update will wait for the updates to complete. The result to your system is delay(blocking). What is difference between DELETE & TRUNCATE commands?

Delete command removes the rows from a table based on the condition that we provide with a WHERE clause. Truncate will actually remove all the rows from a table and there will be no data in the table after we run the truncate command. TRUNCATE TRUNCATE is faster and uses fewer system and transaction log resources than DELETE. TRUNCATE removes removes the data by deallocating the data pages used to store the table’s data, and only the page deallocations are recorded in the transaction log. TRUNCATE removes all rows from a table, but the table structure and its columns, constraints, indexes and so on remain. The counter used by an identity for new rows is reset to the seed for the column. You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY constraint. Because TRUNCATE TABLE is not logged, it cannot activate a trigger. TRUNCATE can not be Rolled back. TRUNCATE is DDL Command. TRUNCATE Resets identity of the table. DELETE DELETE removes removes rows one at a time and records an entry in the transaction log for each deleted row. If you want to retain the identity counter, use DELETE instead. If you want to remove table definition and its data, use the DROP TABLE statement. DELETE Can be used with or without a WHERE clause DELETE Activates Triggers. DELETE Can be Rolled back. DELETE is DML Command. DELETE does not reset identity of the table. Difference between Function and Stored Procedure?


UDF can be used in the SQL statements anywhere in the WHERE/HAVING/SELECT section where as Stored procedures cannot be. UDFs that return tables can be treated as another rowset. This can be used in JOINs with other tables. Inline UDF's can be though of as views that take parameters and can be used in JOINs and other Rowset operations. When is the use of UPDATE_STATISTICS command? This command is basically used when a large processing of data has occurred. If a large amount of  deletions any modification or Bulk Copy into the tables has occurred, it has to update the indexes to take these changes into account. UPDATE_STATISTICS updates the indexes on these tables accordingly. What types of Joins are possible with Sql Server?

Joins are used in queries to explain how different tables are related. Joins also let you select data from a table depending upon data from another table. Types of joins: INNER JOINs, OUTER JOINs, CROSS JOINs. OUTER JOINs are further classified as LEFT OUTER JOINS, RIGHT OUTER JOINS and FULL OUTER JOINS. What is the difference between a HAVING CLAUSE and a WHERE CLAUSE?

Specifies a search condition for a group or an aggregate. HAVING can be used only with the SELECT statement. HAVING is typically used in a GROUP BY clause. When GROUP BY is not used, HAVING behaves like a WHERE clause. Having Clause is basically used only with the GROUP BY function in a query. WHERE Clause is applied to each row before they are part of the GROUP BY function in a query. What is sub-query? Explain properties of sub-query.

Sub-queries are often referred to as sub-selects, as they allow a SELECT statement to be executed Sub-queries arbitrarily within the body of another SQL statement. A sub-query is executed by enclosing enclosing it in a set of  parentheses.. Sub-queries are generally used to return a single row as an atomic value, though they parentheses may be used to compare values against multiple rows with the IN keyword. A subquery is a SELECT statement that is nested within another T-SQL statement. A subquery SELECT statement if executed independently independently of the T-SQL statement, in which it is nested, will return a result set. Meaning a subquery SELECT statement can standalone and is not depended on the statement in which it is nested. A subquery SELECT statement can return any number of values, and can be found in, the column list of a SELECT statement, a FROM, GROUP BY, HAVING, and/or ORDER BY clauses of a T-SQL statement. A Subquery can also be used as a parameter to a function call. Basically a subquery can be used anywhere an expression can be used. Properties of Sub-Query A subquery must be enclosed in the parenthesis. A subquery must be put in i n the right hand of the comparison operator, and A subquery cannot contain a ORDER-BY clause. A query can contain more than one sub-queries. What are types of sub-queries?

Single-row subquery, where the subquery returns only one row. Multiple-row subquery, where the subquery returns multiple rows,.and Multiple column subquery, where the subquery returns multiple columns. What is SQL Profiler?

SQL Profiler is a graphical tool that allows system administrator administrators s to monitor events in an iinstance nstance of  Microsoft SQL Server. Server. You can capture and save data about each event to a file or SQL Server table to analyze later. For example, you can monitor a production environmen environmentt to see which stored procedures are hampering performance by executing too slowly. Use SQL Profiler to monitor only the events in which you are interested. If traces are becoming too large, you can filter them based on the information you want, so that only a subset of the event data is collected. Monitoring too many events adds overhead to the server and the monitoring process and can cause the trace file or trace table to grow very large, especially when the monitoring proces process s takes place over a long period of time. What is User Defined Functions?

User-Defined Functions allow to define its own T-SQL functions that can accept 0 or more parameters and return a single scalar data value or a table data type. What kind of User-Defined Functions can be created?

There are three types of User-Defin User-Defined ed functions in SQL Server 2000 and they are Scalar, Inline TableValued and Multi-statement Table-valued. Scalar User-Defined Function


A Scalar user-defined function returns returns one of the scalar data types. Text, ntext, image i mage and timestamp data types are not supported. These are the type of user-defin user-defined ed functions that most developers are used to in other programming languages. languages. You pass in 0 to many parameters and you get a return value. Inline Table-Value User-Defin User-Defined ed Function An Inline Table-Value user-defined function function returns a table data type and is an exceptional alternative to a view as the user-define user-defined d function can pass parameters into a T-SQL select command and in essence provide us with a parameterized, non-updateable view of the underlying tables. Multi-statementt Table-Value User-Defined Function Multi-statemen A Multi-Statement Table-Value user-defined user-defined function returns a table and is also an exceptional alternative to a view as the function can support support multiple T-SQL statements to build the final result where the view is limited to a single SELECT statement. Also, the ability to pass parameters into a TSQL select command or a group of them gives us the capability to in i n essence create a parameterized, non-updateable view of the data in the underlying tables. Within the create function command you must define the table structure that is being returned. After creating this type of user-defined function, It can be used in the FROM clause of a T-SQL command unlike the behavior found when using a stored procedure which can also return record sets. Which TCP/IP port does SQL Server run on? How can it be changed? SQL Server runs on port 1433. It can be changed from the Network Utility TCP/IP properties –> Port number.both number.bo th on client and the server. What are the authentication modes in SQL Server? How can it be changed?

Windows mode and mixed mode (SQL & Windows). To change authentication mode in SQL Server click Start, Programs, Microsoft SQL Server and click SQL Enterprise Manager to run SQL Enterprise Manager from the Microsoft SQL Server program group. Select the server then from the Tools menu select SQL Server Configuration Properties, and choose the Security page. Where are SQL server users names and passwords are stored in sql server? They get stored in master db in the sysxlogins table. Which command using Query Analyzer will give you the version of SQL server and operating system? SELECT SERVERPROPERTY('productversion'), SERVERPROPERTY ('productlevel'), SERVERPROPERTY ('edition') What is SQL server agent?

SQL Server agent plays an important role in the day-to-day tasks of a database administrator (DBA). It is often overlooked as one of the main tools for SQL Server management. Its purpose is to ease the implementation of tasks for the DBA, with its full-function scheduling engine, which allows you to schedule your own jobs and scripts. Can a stored procedure call itself or recursive stored procedure? How many level SP nesting possible? Yes. Because Transact-SQL supports recursion, you can write stored procedures that call themselves. Recursion can be defined as a method of problem solving wherein the solution is arrived at by repetitively applying it to subsets of the problem. A common application of recursive logic is to perform numeric computations computations that llend end themselves to repetitive evaluation by the same processing steps. Stored procedures are nested when one stored procedure calls another or executes managed code by referencing a CLR routine, type, or aggregate. You can nest stored procedures and managed code references up to 32 levels. What is @@ERROR?

The @@ERROR automatic variable returns the error code of the last Transact-SQL statement. If there was no error, @@ERROR returns zero. Because @@ERROR is reset after each Transact-SQL statement, it must be saved to a variable if it is needed to process it further after checking it. What is Raiseerror?

Stored procedures report errors to client applications via the RAISERROR command. RAISERROR doesn't change the flow of a procedure; it merely displays an error message, sets the @@ERROR automatic variable, and optionally writes the message to the SQL Server error log and the NT application event log. What is log shipping?

Log shipping is the process of automating the backup of database and transaction log files on a production SQL server, and then restoring them onto a standby server. Enterprise Editions only supports log shipping. In log shipping the transactional log file from one server is automatically updated into the backup database on the other server. If one server fails, the other server will have the same db


can be used this as the Disaster Recovery plan. The key feature of log shipping is that is will automatically backup transaction logs throughout throughout the day and automatically restore them on the standby server at defined interval. What is the difference between a local and a global variable?

A local temporary table exists only for the duration of a connection or, if defined inside a compound statement, for the duration of the compound statement. A global temporary table remains in the database permanently, but the rows exist only within a given connection.. When connection are closed, the data in the global temporary table disappears. However, connection the table definition remains with the database for access when database is opened next time. What command do we use to rename a db?

sp_renamedb ‘oldname’ , ‘newname’  sp_renamedb If someone is using db it will not accept sp_renmaedb. In that case first bring db to single user using sp_dboptions. sp_dboption s. Use sp_renamedb to rename database. Use sp_dboptions sp_dboptions to bring database to multi user mode. What is sp_configure commands and set commands?

Use sp_configure sp_configure to display or change server-level settings. To change database-level settings, use ALTER DATABASE. To change settings that affect only the current user session, use the SET statement. What are the different types of replication? Explain.

The SQL Server 2000-supported replication types are as follows: · Transactional · Snapshot · Merge Snapshot replication distributes distributes data exactly as it appears at a specific moment in time and does not monitor for updates to the data. Snapshot replication is best used as a method for replicating data that changes infrequently or where the most up-to-date values (low latency) are not a requirement. When synchronization synchron ization occurs, the entire snapshot is generated and sent to Subscriber Subscribers. s. Transactional replication, an initial snapshot of data is applied at Subscribers, Subscribers, and then when data modifications are made at the Publisher, the individual transactions are captured and propagated to Subscribers. Merge replication is the process of distributing data from Publisher to Subscribers, allowing the Publisher and Subscribers to make updates while connected or disconnected, and then merging the updates between sites when they are connected. What are the OS services that the SQL Server installation adds?

MS SQL SERVER SERVICE, SQL AGENT SERVICE, DTC (Distribution transac co-ordinator) What are three SQL keywords used to change or set someone’s permissions?

GRANT, DENY, and REVOKE. What does it mean to t o have quoted_identifier on? What are the implications of having it off?

When SET QUOTED_IDENTIFIER QUOTED_IDENTIFIER is ON, identifiers can be delimited by double quotation marks, and literals must be delimited by single quotation marks. When SET QUOTED_IDENTIFIER is OFF, identifiers cannot be quoted and must follow all al l Transact-SQL rules for identifiers. What is the STUFF function and how does it differ from fr om the REPLACE function?

STUFF function to overwrite existing characters. Using this syntax, STUFF(str STUFF(string_express ing_expression, ion, start, length, replacement_characters), replacement_characters), string_expr string_expression ession is the string that will have characters substituted, start is the starting position, length is the number of characters characters in the string that are substituted, and replacement_characters replacement_ characters are the new characters interjected into the string. REPLACE function function to replace existing characters of all occurance. Using this syntax REPLACE(string_expression, search_string, replacement_string), where every incidence of  search_string search_str ing found in the string_expression will be replaced with replacement_string. replacement_string. Using query analyzer, name 3 ways to get an accurate count of the number of records in a table? SELECT * FROM table1 SELECT COUNT(*) FROM table1 SELECT rows FROM sysindexes WHERE id = OBJECT_ID(table1) AND indid < 2 How to rebuild Master Database? Shutdown Microsoft SQL Server 2000, and then run Rebuildm.exe. This is located in the Program Files\Microsoft SQL Server\80\Tools\Binn directory. In the Rebuild Master dialog box, click Browse.


In the Browse for Folder dialog box, select the \Data folder on the SQL Server 2000 compact disc or in the shared network directory from which SQL Server 2000 was installed, and then click OK. Click Settings. In the Collation Settings dialog box, verify or change settings used for the master database and all other databases. Initially, the default collation settings are shown, but these may not match the collation selected during setup. You can select the same settings used during setup or select new collation settings. When done, click OK. In the Rebuild Master dialog box, click Rebuild to start the process. The Rebuild Master utility reinstalls the master database. To continue, you may need to stop a server that is running. Source: http://msdn2.microsoft.com/en-us/library/aa197950(SQL.80).aspx What is the basic functions for master, msdb, model, tempdb databases?

The Master database holds information for all databases located on the SQL Server instance and is the glue that holds the engine together. Because SQL Server cannot start without a functioning master database, you must administer this database with care. The msdb database stores information regarding database backups, SQL Agent information, DTS packages, SQL Server jobs, and some replication information such as for log shipping. The tempdb holds temporary objects such as global and local temporary tables and stored procedures. procedures. The model is essentially a template database used in the creation of any new user database created in the instance. What are primary keys and foreign keys?

Primary keys are the unique identifiers for each row. They must contain unique values and cannot be null. Due to their importance in relational databases, Primary keys are the most fundamental of all keys and constraints. A table can have only one Primary key. Foreign keys are both a method of ensuring data integrity and a manifestation of the relationship between tables. What is data integrity? Explain constraints?

Data integrity is an important feature in SQL Server. When used properly, it ensures that data is accurate, correct, and valid. It also acts as a trap for otherwise undetectable bugs within applications. A PRIMARY KEY constraint is a unique identifier for a row within a database table. Every table should have a primary key constraint to uniquely identify each row and only one primary key constraint can be created for each table. The primary key constraints are used to enforce entity integrity. A UNIQUE constraint enforces the uniqueness of the values in a set of columns, so no duplicate values are entered. The unique key constraints are used to enforce entity integrity as the primary key constraints. A FOREIGN KEY constraint prevents any actions that would destroy links between tables with the corresponding correspon ding data values. A foreign key in one table points to a primary key in another table. Foreign keys prevent actions that would leave rows with foreign key values when there are no primary keys with that value. The foreign key constraints are used to enforce referential integrity. A CHECK constraint is used to limit the values that can be placed in a column. The check constraints are used to enforce domain integrity. A NOT NULL constraint enforces that the column will not accept null values. The not null constraints are used to enforce domain integrity, as the check constraints. What are the properties of the Relational tables?

Relational tables have six properties: · Values are atomic. · Column values are of the same kind. · Each row is unique. · The sequence of columns is insignificant. · The sequence of rows is insignificant. · Each column must have a unique name. What is De-normalization De-normalization? ?

De-normalization is the process of attempting to optimize the performance of a database by adding De-normalization redundantt data. It is sometimes necessary because curr redundan current ent DBMSs implement the relational model poorly. A true relational DBMS would allow for a fully normalized database at the logical level, while providing physical storage of data that is tuned for high performance. De-normalization is a technique to move from higher to lower normal forms of database modeling in order to speed up database access. How to get @@error and @@rowcount at the same time? If @@Rowcount is checked after Error Error checking statement then it will have 0 as the value of 


@@Recordcount as it would have been reset. And if @@Recordcount is checked before the error-checking statement then @@Error would get reset. To get @@error and @@rowcount at the same time do both in same statement and store them in local variable. SELECT @RC = @@ROWCOUNT, @ER = @@ERROR What is Identity?

Identity (or AutoNumber) is a column that automatically generates numeric values. A start and increment value can be set, but most DBA leave these at 1. A GUID column also generates numbers, the value of this cannot be controled. Identity/GUID columns do not need to be indexed. What is a Scheduled Jobs or What is a Scheduled Tasks?

Scheduled tasks let user automate processes that run on regular or predictable cycles. User can schedule administrative administrative tasks, such as cube processing, to run during times of slow business activity. User can also determine the order in which tasks run by creating job steps within a SQL Server Agent  job. E.g. Back up database, Update Stats of Tables. Job steps give user control over flow of execution. If one job fails, user can configure SQL Server Agent to continue to run the remaining tasks or to stop execution. What is a table called, if it does not have neither Cluster nor Non-cluster Index? What is it used for?

Unindexed table or Heap. Microsoft Press Books and Book On Line (BOL) refers it as Heap. A heap is a table that does not have a clustered index and, theref therefore, ore, the pages are not linked by pointers. The IAM pages are the only structures that link the pages in a table together. Unindexed tables are good for fast storing of data. Many times it is better to drop all indexes from table and than do bulk of inserts and to restore those indexes after that. What is BCP? When does it used?

BulkCopy is a tool used to copy huge amount of data from tables and views. BCP does not copy the structures structure s same as source to destination. How do you load large data to the SQL server database? BulkCopy is a tool used to copy huge amount of data from tables. BULK INSERT command helps to Imports a data file into a database table or view in a user-specified format. format. Can we rewrite subqueries into simple select statements or with joins? Subqueries Subquer ies can often be re-written to use a standard outer join, resulting in faster performance. As we may know, an outer join uses the plus sign (+) operator to tell the database to return all non-matching rows with NULL values. Hence we combine the outer join with a NULL test in the WHERE clause to reproduce the result set without using a sub-query. Can SQL Servers linked to other servers like Oracle? SQL Server can be lined to any server provided it has OLE-DB provider from Microsoft to allow a link. E.g. Oracle has a OLE-DB provider for oracle that Microsoft provides to add it as linked server to SQL Server group. How to know which index a table is using? SELECT table_name,index_name FROM user_constraints How to copy the tables, schema and views from one SQL server to another? Microsoft SQL Server 2000 Data Transformation Services (DTS) is a set of graphical tools and programmable programmab le objects that lets user extract, transform, and consolidate data from disparate sources into single or multiple destinations. What is Self Join?

This is a particular case when one table joins to itself, with one or two aliases to avoid confusion. A self   join can be of any type, as long as the joined tables are the same. A self join is rather unique in that it involves a relationship with only one table. The common example is when company have a hierarchal reporting structure whereby one member of staff reports to another. What is Cross Join?

A cross join that does not have a WHERE clause produces produces the Cartesian product of the tables involved in the join. The size of a Cartesian product result set is the number of rows in the first table multiplied by the number of rows in the second table. The common example is when company wants to combine each product with a pricing table to analyze each product at each price. Which virtual table does a trigger use? Inserted and Deleted. List few advantages of Stored Procedure. · Stored procedure can reduced network traffic and latency, boosting application performance. · Stored procedure execution plans can be reused, staying cached in SQL Server's memory, reducing server overhead.


· Stored procedures help promote code reuse. · Stored procedures can encapsulate logic. You can change stored procedure code without affecting clients. · Stored procedures provide better security to your data. What is DataWarehousin DataWarehousing? g?

· Subject-oriented, Subject-oriented, meaning that the data in i n the database is organized so that all the data elements relating to the same real-world event or object are linked together; · Time-variant, meaning that the changes to the data in the database are tracked and recorded so that reports can be produced showing changes over time; · Non-volatile, meaning that data in the database is never over-wr over-written itten or deleted, once committed, the data is static, read-only, but retained for future reporting; · Integrated, meaning that the database contains data from most or all of an organization's operational applications, and that this data is made consistent. What is OLTP(OnLin OLTP(OnLine e Transaction Processing)?

In OLTP - online transaction processing systems relational database design use the discipline of data modeling and generally follow the Codd rules of data normalization in order to ensure absolute data integrity. Using these rules complex information is broken down into its most simple structures (a table) where all of the individual atomic level elements relate to each other and satisfy the normalization rules. How do SQL server 2000 and XML linked? Can XML be used to access data? FOR XML (ROW, AUTO, EXPLICIT) You can execute SQL queries against existing relational databases to return results as XML rather than standard rowsets. These queries can be executed directly or from within stored procedures. To retrieve XML results, use the FOR XML clause of the SELECT statement and specify an XML mode of RAW, AUTO, or EXPLICIT. OPENXML OPENXML is a Transact-SQL keyword that provides a relational/rowset view over an in-memory XML document. OPENXML OPENXML is a rowset provider similar to a table or a view. OPENXML provides a way to access XML data within the Transact-SQL context by transferring data from an XML document into the relational tables. Thus, OPENXML allows you to manage an XML document and its interaction with the relational environment. What is an execution plan? When would you use it? How would you view the execution plan?

An execution plan is basically a road map that graphically or textually shows the data retrieval methods chosen by the SQL Server query optimizer for a stored procedure or ad-hoc query and is a very useful tool for a developer to understand the performance characteristics of a query or stored procedure since the plan is the one that SQL Server will place in its cache and use to execute the stored procedure or query. From within Query Analyzer is an option called "Show Execution Plan" (located on the Query drop-down drop-dow n menu). If this option is turned on iitt will display query execution plan in separate window when query is ran again.


.NET Interview Questions Basic .NET Framework

What is a IL? Twist :- What is MSIL or CIL , What is JIT? What is a CLR? What is a CTS? What is a CLS(Common Language Specification)? What is a Managed Code? What is a Assembly ? What are different types of Assembly? What is NameSpace? What is Difference between NameSpace and Assembly? If you want to view a Assembly how to you go about it ? Twist : What is ILDASM ? What is Manifest? Where is version information stored of a assembly ? Is versioning applicable to private assemblies? What is GAC ? Twist :- What are situations when you register .NET assembly in GAC ? What is concept of strong names ? Twist :- How do we generate strong names or what is the process of generating strong names , What is use of SN.EXE , How do we apply strong names to assembly ? , How do you sign an assembly ? How to add and remove a assembly from GAC? What is Delay signing ? What is garbage collection? Can we force garbage collector to run ? What is reflection? What are different type of JIT ? What are Value types and Reference types ? What is concept of Boxing and Unboxing ? What’s difference between VB.NET and C# ? What’s difference between System exceptions and Application exceptions? What is CODE Access security? What is a satellite assembly? How to prevent my .NET DLL to be decompiled? What’s the difference between Convert.toString and .toString() method ? What is Native Image Generator (Ngen.exe)? (Ngen.exe)? We have two version of the same assembly in GAC? I want my client to make choice of  which assembly to choose? What is CodeDom? .NET Interoperability

How can we use COM Components in .NET? Twist : What is RCW ? Once i have developed the COM wrapper do i have to still register the COM in registry? How can we use .NET components in COM? Twist :- What is CCW (COM callable wrapper) ?, What caution needs to be taken in order that .NET components is compatible with COM ? How can we make Windows API calls in .NET? When we use windows API in .NET is it managed or unmanaged code ? What is COM ? What is Reference counting in COM ? Can you describe IUKNOWN interface in short ? Can you explain what is DCOM ? How do we create DCOM object in VB6? How to implement DTC in .NET ? How many types of Transactions are there in COM + .NET ? How do you do object pooling in .NET ? What are types of compatibility in VB6? What is equivalent for regsvr32 exe in .NET ? Threading


What is Multi-tasking ? What is Multi-threading ? What is a Thread ? Did VB6 support multi-threading ? Can we have multiple threads in one App domain ? Which namespace has threading ? Can you explain in brief how can we implement threading ? How can we change priority and what the levels of priority are provided by .NET ? What does Addressof operator do in background ? How can you reference current thread of the method ? What's Thread.Sleep() in threading ? How can we make a thread sleep for infinite period ? What is Suspend and Resume in Threading ? What the way to stop a long running thread ? How do i debug thread ? What's Thread.Join() in threading ? What are Daemon thread's and how can a thread be created as Daemon? When working with shared data in threading how do you implement synchronization ? Can we use events with threading ? How can we know a state of a thread? What is a monitor object? What are wait handles ? Twist :- What is a mutex object ? what is ManualResetEvent and AutoResetEvent ? What is ReaderWriter Locks ? How can you avoid deadlock in threading ? What’s difference between thread and process? Remoting and Webservices

What is a application domain? What is .NET Remoting ? Which class does the remote object has to inherit ? What are two different types of remote object creation mode in .NET ? Describe in detail Basic of SAO architecture of Remoting? What are the situations you will use singleton architecture in remoting ? What is fundamental of published or precreated objects in Remoting ? What are the ways client can create object on server in CAO model ? Are CAO stateful in nature ? In CAO model when we want client objects to be created by “NEW” keyword is there any precautions to be taken ? Is it a good design practice to distribute the implementation to Remoting Client ? What is LeaseTime,Spon LeaseTime,SponsorshipTime sorshipTime ,RenewonCallTime and LeaseManage LeaseManagerPollTime? rPollTime? Which config file has all the supported channels/protocol ? How can you specify remoting parameters using Config files ? Can Non-Default constructors be used with Single Call SAO? Twist :- What are the limitation of constructors for Single call SAO ? How can we call methods in remoting Asynchronously ? What is Asynchronous One-Way Calls ? What is marshalling and what are different kinds of marshalling ? What is ObjRef object in remoting ? What is a WebService ? What is UDDI ? What is DISCO ? What is WSDL? What the different phase/steps of acquiring a proxy object in Webservice ? What is file extension of Webservices Webservices ? Which attribute is used in order that the method can be used as WebService ? What are the steps to create a webservice and consume consume it ? Do webservice have state ? Caching Concepts

What is application object ? What’s the difference between Cache object and application object ? How can get access to cache object ? What are dependencies in cache and types of dependencies ? Can you show a simple code showing file dependency in cache ?


What is Cache Callback in Cache ? What is scavenging ? What are different types of caching using cache object of ASP.NET? How can you cache different version of same page using ASP.NET cache object ? How will implement Page Fragment Caching ? What are ASP.NET session and compare ASP.NET session with classic ASP session variables? Which various modes of storing ASP.NET session ? Is Session_End event supported in all session modes ? What are the precautions you will take in order that StateServer Mode work properly ? What are the precautions you will take in order that SQLSERVER Mode work properly ? Where do you specify session state mode in ASP.NET ? What are the other ways you can maintain state ? What are benefits and Limitation of using Hidden fields ? What is ViewState ? Do performance vary for viewstate according to User controls ? What are benefits and Limitation of using Viewstate for state managemen management? t? How an you use Hidden frames to cache client data ? What are benefits and Limitation of using Hidden frames? What are benefits and Limitation of using Cookies? What is Query String and What are benefits and Limitation of using Query Strings? OOPS What is Object Oriented Programming ? What’s a Class ? What’s a Object ? What’s the relation between Classes and Objects ? What are different properties provided by Object-orien Object-oriented ted systems ? Twist :- Can you explain different properties of Object Oriented Systems? Twist :- What’s difference between Association , Aggregation and Inheritance relationships? relationships? How can we acheive inheritance in VB.NET ? What are abstract classes ? What’s a Interface ? What is difference between abstract classes and interfaces? What is a delegate ? What are event’s ? Do events have return type ? Can event’s have access modifiers ? Can we have shared events ? What is shadowing ? What’s difference between Shadowing and Overriding ? What’s difference between delegate and events? If we inherit a class do the private variables also get inherited ? What are different accessibility levels defined in .NET . NET ? Can you prevent a class from overriding ? What’s the use of “MustInherit” keyword in VB.NET ? Why can not you specify accessibility modifier in Interface ? What are similarities between Class and structure ? What’s the difference between Class and structure’s ? What does virtual keyword mean ? What are shared (VB.NET)/Static(C#) (VB.NET)/Static(C#) variables? What is Dispose method in .NET ? Whats the use of “OverRides” and “Overridable” keywords ? Where are all .NET Collection classes located ? What is ArrayList ? What’s a HashTable ? Twist :- What’s difference between HashTable and ArrayList ? What are queues and stacks ? What is ENUM ? What is nested Classes ? What’s Operator Overloading in .NET? In below sample code if we create a object of class2 which constructor constructor will fire first ? What’s the significance of Finalize method in .NET? Why is it preferred to not use finalize for clean up? How can we suppress a finalize method? What’s the use of DISPOSE method?


How do I force the Dispose method to be called automatically, as clients can forget to call Dispose method? In what instances you will declare a constructor to be private? Can we have different access modifiers on get/set methods of a property ? If we write a goto or a return statement in try and catch block will the finally block execute ? What is Indexer ? Can we have static indexer in C# ? In a program there are multiple catch blocks so can it happen that two catch blocks are executed ? What is the difference between System.String and System.StringBuilder classes? ASP.NET

What’s the sequence in which ASP.NET events are processed ? In which event are the controls fully loaded ? How can we identify that the Page is PostBack ? How does ASP.NET maintain state in between subsequent request ? What is event bubbling ? How do we assign page specific attributes ? Administrator wants to make a security check that no one has tampered with ViewState , how can he ensure this ? 153 What’s the use of @ Register directives ? What’s the use of SmartNavigation property ? What is AppSetting Section in “Web.Config” file ? Where is ViewState information stored ? What’s the use of @ OutputCache directive in ASP.NET? How can we create custom controls in ASP.NET ? How many types of validation controls are provided by ASP.NET ? Can you explain what is “AutoPostBack” feature in ASP.NET ? How can you enable automatic paging in DataGrid ? What’s the use of “GLOBAL.ASAX” file ? What’s the difference between “Web.config” and “Machine.Config” ? What’s a SESSION and APPLICATION object ? What’s difference between Server.Transfer and response.Redirect ? What’s difference between Authentication and authorization? What is impersonation in ASP.NET ? Can you explain in brief how the ASP.NET authentication process works? What are the various ways of authentication techniques in ASP.NET? How does authorization work in ASP.NET? What’s difference between Datagrid Datagrid , Datalist and repeater ? From performance point of view how do they rate ? What’s the method to customize columns in DataGrid? How can we format data inside DataGrid? How will decide the design consideration to take a Datagrid , datalist or repeater ? Difference between ASP and ASP.NET? What are major events in GLOBAL.ASAX file ? What order they are triggered ? Do session use cookies ? How can we force all the validation control to run ? How can we check if all the validation control are valid and proper ? If you have client side validation is enabled in your Web page , Does that mean server side code is not run? Which JavaScript JavaScript file is referenc referenced ed for validating the validators at the client side ? How to disable client side script in validators? I want to show the entire validation error message in a message box on the client side? You find that one of your validation is very complicated and does not fit in any of the validators , so what will you do ? What is Tracing in ASP.NET ? How do we enable tracing ? What exactly happens when ASPX page is requested from Browser? How can we kill a user session ? How do you upload a file in ASP.NET ? How do I send email message from ASP.NET ? What are different IIS isolation levels? ASP used STA threading model , whats the threading model used for ASP.NET ?


Whats the use of <%@ page aspcompat=true %> attribute ? Explain the differences between Server-side and Client-side code? Can you explain Forms authentication in detail ? How do I sign out in forms authentication ? If cookies are not enabled at browser end does form Authentication work? How to use a checkbox in a datagrid? What are the steps to create a windows service in VB.NET ? What’s the difference between “Web farms” and “Web garden”? How do we configure “WebGarden”? What is the main difference between Gridlayout and FlowLayout FlowLayout ? .NET Architecture

What are design patterns ? What’s difference between Factory and Abstract Factory Pattern’s? What’s MVC pattern? Twist: - How can you implement MVC pattern in ASP.NET? How can we implement singleton pattern in .NET? How do you implement prototype pattern in .NET? Twist: - How to implement cloning in .NET ? , What is shallow copy and deep copy ? What are the situations you will use a Web Service and Remoting in projects? projects? Can you give a practical implementation of FAÇADE patterns? How can we implement observer pattern in .NET? What is three tier architecture? Have you ever worked with Microsoft Application Blocks, if yes then which? What is Service Oriented architecture? What are different ways you can pass data between tiers? What is Windows DNA architecture? What is aspect oriented programming? ADO.NET

What is the namespace in which .NET has the data functiona functionality lity classes ? Can you give a overview of ADO.NET architecture ? What are the two fundamen fundamental tal objects in ADO.NET ? What is difference between dataset and datareader ? What are major difference between classic ADO and ADO.NET ? What is the use of connection object ? What is the use of command objects and what are the methods provided by the command object ? What is the use of dataadapter ? What are basic methods of Dataadapter ? What is Dataset object? What are the various objects in Dataset ? How can we connect to Microsoft Access , Foxpro , Oracle etc ? How do we connect to SQL SERVER , which namespace do we use ? How do we use stored procedure in ADO.NET and how do we provide parameters to the stored procedures? How can we force the connection object to close after my datareader is closed ? I want to force the datareader to return only schema of the datastore rather than data ? How can we fine tune the command object when we are expecting a single row or a single value ? Which is the best place to store connectionstring in .NET projects ? What are steps involved to fill a dataset ? Twist :- How can we use dataadapter to fill a dataset ? What are the various methods provided by the dataset object to generate XML? How can we save all data from dataset ? How can we check that some changes have been made to dataset since it was loaded ? Twist :- How can we cancel all changes done in dataset ? , How do we get values which are changed in a dataset ? How can we add/remove row’s in “DataTable” object of “DataSet” ? What’s basic use of “DataView” ? What’s difference between “DataSet” and “DataReader” ? Twist :- Why is DataSet slower than DataReader ? How can we load multiple tables in a DataSet ? How can we add relation’s between table in a DataSet ? What’s the use of CommandBuilder ? What’s difference between “Optimistic” and “Pessimistic” locking ?


How many way’s are there to implement locking in ADO.NET ? How can we perform transactions in .NET? What’s difference between Dataset. clone and Dataset. copy ? Can you explain the difference between an ADO.NET Dataset and an ADO Recordset? Explain in detail the fundamen fundamental tal of connection pooling? pooling? What is Maximum Pool Size in ADO.NET Connection String? How to enable and disable connection pooling? SQL SERVER 

What is normalization? What are different type of normalization? What is denormalization ? What is a candidate key ? What are different types of joins and whats the difference between them ? What are indexes and What is the difference between clustered and nonclustered indexes? How can you increase SQL performance ? What is the use of OLAP ? What's a measure in OLAP ? What are dimensions in OLAP ? What are levels in dimensions ? What are fact tables and dimension tables in OLAP ? Twist :- can you explain the star schema for OLAP ? What is DTS? What is fillfactor ? Twist :- When does plage split occurs ? What is RAID and how does it work ? What's the difference between DELETE TABLE and TRUNCATE TABLE commands? What are the problems that can occur if you do not implement locking properly in SQL SERVER ? What are different transaction levels in SQL SERVER ? Twist :- what are different types of locks in SQL SERVER ? What are different locks in SQL SERVER ? Can we suggest locking hints to SQL SERVER ? What is LOCK escalation? What are the different ways of moving data/databases between servers servers and databases in SQL Server? What are advantages of SQL 2000 over SQl 7.0 ? What is the difference between a HAVING CLAUSE and a WHERE CLAUSE? What is difference between UNION and UNION ALL SQL syntax ? How can you raise custom errors from stored procedure ? What is ACID fundamental and what are transactions in SQL SERVER ? What is DBCC? What is purpose of Replication ? What are different type of replication supported by SQL SERVER ? What is BCP utility in SQL SERVER ? What are different types of triggers in SQl SERVER 2000 ? If we have multiple AFTER Triggers on table how can we define the sequence of the triggers ? What is SQl injection ? What’s the difference between Stored Procedure (SP) and User Defined Function (UDF)? UML

What is UML? How many types of diagrams are there in UML ? Twist :- Explain in short all types of diagrams in UML ? What are advantages of using UML? Twist: - What is Modeling and why UML ? What’s the sequence of UML diagrams in project? Twist: - How did you implement UML in your project? Just a small Twist: - Do I need all UML diagrams in a project? Give a small brief explanation of all Elements in activity diagrams? Explain Different elements of a collaboration diagram ? Explain Component diagrams ? Explain all parts of a deployment diagram? Describe various components in sequence diagrams? What are the element in State Chart diagrams ?


Describe different elements in Static Chart diagrams ? Explain different different elements of a Use Case ? Twist: - What’s difference between Activity and sequence diagrams?(I leave this to the readers) Project Management

What is project management? Is spending in IT project’s constant through out the project? Who is a stakeholder ? Can you explain project life cycle ? Twist :- How many phases are there in software project ? Are risk constant through out the project ? Can you explain different software development life cycles ? What is triple constraint triangle in project management ? What is a project baselines ? What is effort variance? How is normally a project management plan document organized ? How do you estimate a project? What is CAR (Causal Analysis and Resolution Resolution)? )? What is DAR (Decision Analysis and Resolution)? What is a fish bone diagram ? Twist:- What is Ishikawa diagram ? What is pareto principle ? Twist :- What is 80/20 principle ? How do you handle change request? What is internal change request? What is difference between SITP and UTP in testing ? What are the software you have used for project management? What are the metrics followed in project management? Twist: - What metrics will you look at in order to see the project is moving successfully? You have people in your team who do not meet there deadlines or do not perform what are the actions you will take ? Twist :- Two of your resources have conflict’s between them how would you sort it out ? What is black box testing and White box testing? What’s the difference between Unit Testing, Assembly Testing and Regression testing? What is V model in testing? How do you start a project? How did you do resource allocations? How do you do code reviews ? What is CMMI? What are the five levels in CMMI? What is continuous and staged representation? Can you explain the process areas? What is SIX sigma? What is DMAIC and DMADV ? What are the various roles in i n Six Sigma implementation? What are function points? Twist: - Define Elementary process in FPA? What are different types of elementary process in FPA? What are the different elements in Functions points? Can you explain in GSC and VAF in function points? What are unadjusted function points and how is it i t calculated? Can you explain steps in function points? What is the FP per day in your current company? Twist :- What is your company’s productivity productivity factor ? Do you know Use Case points? What is COCOMO I, COCOMOII and COCOMOIII? What is SMC approach of estimation? How do you estimate maintenance project and change requests? XML

What is XML? What is the version information in XML? What is ROOT element in XML? If XML does not have closing tag will it work?


Is XML case sensitive? What’s the difference between XML and HTML? Is XML meant to replace HTML? Can you explain why your project needed XML? What is DTD (Document Type definition)? What is well formed XML? What is a valid XML? What is CDATA section in XML? What is CSS? What is XSL? What is Element and attributes in XML? Which are the namespaces in .NET used for XML? What are the standard ways of parsing XML document? In What scenarios will you use a DOM parser and SAX parser? How was XML handled during COM times? What’s the main difference between MSML and .NET Framework XML classes? What are the core functionalities in XML .NET framework? Can you explain in detail those functionalities? What is XSLT? Define XPATH? What’s the concept of XPOINTER? What is an XMLReader Class? What is XMLTextRead XMLTextReader? er? How do we access attributes using “XmlReader”? Explain simple Walk through of XmlReader ? What does XmlValidatingReader class do?

SQL Server Interview Questions Database Concepts

What is database or database management systems (DBMS)? What’s difference between DBMS and RDBMS ? What are CODD rules? Is access database a RDBMS? What’s the main difference between ACCESS and SQL SERVER? What’s the difference between MSDE and SQL SERVER 2000? What is SQL SERVER Express 2005 Edition? What is SQL Server 2000 Workload Governor? What’s the difference between SQL SERVER 2000 and 2005? What are E-R diagrams? How many types of relationship exist in database designing? What is normalization? What are different type of normalization? What is denormalization ? Can you explain Fourth Normal Form? Can you explain Fifth Normal Form? What’s the difference between Fourth and Fifth normal form? Have you heard about sixth normal form? What is Extent and Page? What are the different sections in Page? What are page splits? In which files does actually SQL Server store data? What is Collation in SQL Server? Can we have a different collation for database and table? SQL

Revisiting basic syntax of SQL? What are “GRANT” and “REVOKE’ statements? What is Cascade and Restrict in DROP table SQL? How to import table using “INSERT” statement? What is a DDL, DML and DCL concept in RDBMS world? What are different types of joins in SQL? What is “CROSS JOIN”? You want to select the first record in a given set of rows?


How do you sort in SQL? How do you select unique rows using SQL? Can you name some aggregate function is SQL Server? What is the default “SORT” order for a SQL? What is a self-join? What’s the difference between DELETE and TRUNCATE ? Select addresses which are between ‘1/1/2004’ and ‘1/4/2004’? What are Wildcard operators in SQL Server? What’s the difference between “UNION” and “UNION ALL” ? What are cursors and what are the situations you will use them? What are the steps to create a cursor? What are “Global” the different Cursor Types? and “Local” cursors? What is “Group by” clause? What is ROLLUP? What is CUBE? What is the difference between “HAVING” and “WHERE” clause? What is “COMPUTE” clause in SQL? What is “WITH TIES” clause in SQL? What does “SET ROWCOUNT” syntax achieves? What is a Sub-Query? What is “Correlated Subqueries”? Subqueries”? What is “ALL” and “ANY” operator? What is a “CASE” statement in SQL? What does COLLATE Keyword in SQL signify? What is CTE (Common Table Expression)? Why should you use CTE rather than simple views? What is TRY/CATCH block in T-SQL? What is PIVOT feature in SQL Server? What is UNPIVOT? What are RANKING functions? What is ROW_NUMBER()? What is RANK() ? What is DENSE_RANK()? What is NTILE()? What is SQl injection ? .NET Integration

What are steps to load a .NET code in SQL SERVER 2005? How can we drop an assembly from SQL SERVER? Are changes made to assembly updated automatically in database? Why do we need to drop assembly for updating changes? How to see assemblies loaded in SQL Server? I want to see which files are linked with which assemblies? Does .NET CLR and SQL SERVER run in different process? Does .NET controls SQL SERVER or is it vice-versa? Is SQLCLR configured by default? How to configure CLR for SQL SERVER? Is .NET feature loaded by default in SQL Server? How does SQL Server control .NET run-time? What’s a “SAND BOX” in SQL Server 2005? What is an application domain? How are .NET Appdomain allocated in SQL SERVER 2005? What is Syntax for creating a new assembly in SQL Server 2005? Do Assemblies loaded in database need actual .NET DLL? You have a assembly which is dependent on other assemblies, will SQL Server load the dependentt assemblies? dependen Does SQL Server handle unmanaged resources? What is Multi-tasking Multi-tasking? ? What is Multi-thread Multi-threading? ing? What is a Thread ? Can we have multiple threads in one App domain? What is Non-pree Non-preemptive mptive threading? What is pre-emptive threading? threading? Can you explain threading model in SQL Server?


How does .NET and SQL Server thread work? How is exception in SQLCLR code handled? Are all .NET libraries allowed in SQL Server? What is “Hostprot “Hostprotectionattribute” ectionattribute” in SQL Server 2005? How many types of permission level are there for an assembly? In order that an assembly gets loaded in SQL Server what type of checks are done? Can you name system tables for .NET assemblies? Are two version of same assembly allowed in SQL Server? How are changes made in assembly replicated? Is it a good practice to drop a assembly for changes? In one of the projects following steps where done, will it work? Whatdo does Alteranassembly with uncheck unchecked ed data signify? How I drop assembly? Can we create SQLCLR using .NET framework 1.0? While creating .NET UDF what checks should be done? How do you define a function from the .NET assembly? Can you compare between T-SQL and SQLCLR? With respect to .NET is SQL SERVER case sensitive? Does case sensitive rule apply for VB.NET? Can nested classes be accessed in T-SQL? Can we have SQLCLR procedure input as array? Can object datatype be used in SQLCLR? How’s precision handled for decimal datatypes in .NET? How do we define INPUT and OUTPUT parameters in SQLCLR? Is it good to use .NET datatypes in SQLCLR? How to move values from SQL to .NET datatypes? What is System.Data.SqlSe System.Data.SqlServer? rver? What is SQLContex SQLContext? t? Can you explain essential steps to deploy SQLCLR? How do create function in SQL Server using .NET? How do we create trigger using .NET? How to create User Define Functions using .NET? How to create aggregates using .NET? What is Asynchronous support in ADO.NET? What is MARS support in ADO.NET? What is SQLbulkcopy object in ADO.NET? How to select range of rows using ADO.NET? What are different types of triggers in SQl SERVER 2000 ? If we have multiple AFTER Triggers on table how can we define the sequence of the triggers ? How can you raise custom errors from stored procedure ? ADO.NET

Which are namespaces for ADO.NET? Can you give a overview of ADO.NET architecture? What are the two fundamental objects in ADO.NET? What is difference between dataset and datareader? What are major difference between classic ADO and ADO.NET? What is the use of connection object? What are the methods provided by the command object? What is the use of “Dataadapter”? What are basic methods of “Dataadapter” “Dataadapter”? ? What is Dataset object? What are the various objects in Dataset? How can we connect to Microsoft Access, FoxPro, Oracle etc? What’s the namespace to connect to SQL Server? How do we use stored procedure in ADO.NET? How can we force the connection object to close? I want to force the datareader to return only schema? Can we optimize command object when there is only one row? Which is the best place to store connection connectionstring? string? What are steps involved to fill a dataset? What are the methods provided by the dataset for XML? How can we save all data from dataset? How can we check for changes made to dataset?


How can we add/remove row’s in “DataTable” object of “DataSet”? What’s basic use of “DataView”? What’s difference between “DataSet” and “DataReader”? How can we load multiple tables in a DataSet? How can we add relation’s between table in a DataSet? What’s the use of CommandBuilder? What’s difference between “Optimistic” and “Pessimistic” locking? How many way’s are there to implement locking in ADO.NET? How can we perform transactions in .NET? What’s difference between Dataset. clone and Dataset. copy? Whats the difference between Dataset and ADO Recordset? Notification Services

What are notification services? What are basic components of Notification services? Can you explain architectur architecture e of Notification Services? Which are the two XML files needed for notification services? What is Nscontrols command? What are the situations you will use “Notification” Services? Service Broker

What do we need Queues? What is “Asynchronous” communication? What is SQL Server Service broker? What are the essential components of SQL Server Service broker? What is the main purpose of having Conversation Group? How to implement Service Broker? How do we encrypt data between Dialogs? XML Integration

What is XML? What is the version information in XML? What is ROOT element in XML? If XML does not have closing tag will it work? Is XML case sensitive? What’s the difference between XML and HTML? Is XML meant to replace HTML? Can you explain why your project needed XML? What is DTD (Document Type definition)? What is well formed XML? What is a valid XML? What is CDATA section in XML? What is CSS? What is XSL? What is Element and attributes in XML? Can we define a column as XML? How do we specify the XML data type as typed or untyped? How can we create the XSD schema? How do I insert in to a table which has XSD schema attached to it? What is maximum size for XML datatype? What is Xquery? What are XML indexes? What are secondary XML indexes? What is FOR XML in SQL Server? Can I use FOR XML to generate SCHEMA of a table and how? What is the OPENXML statement in SQL Server? I have huge XML file which we want to load in database? How to call stored procedure using HTTP SOAP? What is XMLA? Data Warehousing/Data Mining

What is “Data Warehousing”? What are Data Marts? What are Fact tables and Dimension Tables? What is Snow Flake Schema design in i n database?


What is ETL process in Data warehousing? How can we do ETL process in SQL Server? What is “Data mining”? Compare “Data mining” and “Data Warehousing”? What is BCP? How can we import and export using BCP utility? During BCP we need to change the field position or eliminate some fields how can we achieve this? What is Bulk Insert? What is DTS? Can you brief about the Data warehouse project you worked on? What Processing)system? System? What is is an an OLTP OLAP (Online (On-lineTransaction Analytical processing) What is Conceptual, Logical and Physical model? What is Data purging? What is Analysis Services? What are CUBES? What are the primary ways to store data in OLAP? What is META DATA information in Data warehousing projects? What is multi-dimension multi-dimensional al analysis? What is MDX? How did you plan your Data ware house project? What are different deliverables according to phases? Can you explain how analysis service works? What are the different problems that “Data mining” can solve? What are different stages of “Data mining”? What is Discrete and Continuou Continuous s data in Data mining world? What is MODEL is Data mining world? DB)How are models actually derived? What is a Decision Tree Algorithm? Can decision tree be implemented using SQL? What is Naïve Bayes Algorithm? Explain clustering algorithm? Explain in detail Neural Networks? What is Back propagation in Neural Networks? What is Time Series algorithm in data mining? Explain Association algorithm in Data mining? What is Sequence clustering algorithm? What are algorithms provided by Microsoft in SQL Server? How does data mining and data warehousing work together? What is XMLA? What is Discover and Execute in XMLA? Integration Services/DTS

What is Integration Services import / export wizard? What are prime components in Integration Services? How can we develop a DTS project in Integration Services? Replication

Whats the best way to update data between SQL Servers? What are the scenarios you will need multiple databases with schema? How will you plan your replication? What are publisher, distributor and subscriber in “Replication”? What is “Push” and “Pull” subscription? Can a publication support push and pull at one time? What are different models / types of replication? What is Snapshot replication? What are the advantages and disadvantages of using Snapshot replication? replication? What type of data will qualify for “Snapshot replication”? What’s the actual location where the distributor runs? Can you explain in detail how exactly “Snapshot Replication” works? What is merge replication? How does merge replication works? What are advantages and disadvantages of Merge replication? What is conflict resolution in Merge replication?


What is a transactional replication? Can you explain in detail how transactional replication works? What are data type concerns during replications? replications? Reporting Services

Can you explain how can we make a simple report in reporting services? How do I specify stored procedures in Reporting Services? What is the architectur architecture e for “Reporting Services “? Database Optimization

What are indexes? What B-Trees? I haveare a table which has lot of inserts, is it a good database design to create indexes on that table? What are “Table Scan’s” and “Index Scan’s”? What are the two types of indexes and explain them in detail? What is “FillFactor” concept in indexes? What is the best value for “FillFactor”? What are “Index statistics”? How can we see statistics of an index? How do you reorganize your index, once you find the problem? What is Fragmentation Fragmentation? ? How can we measure Fragmentation? How can we remove the Fragmented spaces? What are the criteria you will look in to while selecting an index? What is “Index Tuning Wizard”? What is an Execution plan? How do you seejoin, the hash SQL plan textual What is nested join in and mergeformat? join in SQL Query plan? What joins are good in what situations? What is RAID and how does it work ? Transaction and Locks

What is a “Database Transactions “? What is ACID? What is “Begin Trans”, “Commit Tran”, “Rollback Tran” and “Save Tran”? What are “Checkpoint’s” in SQL Server? What are “Implicit Transactions Transactions”? ”? Is it good to use “Implicit Transactions”? 315 What is Concurrency? How can we solve concurrency problems? What kind of problems occurs if we do not implement proper locking strategy? What are “Dirty reads”? reads”? What are “Unrepeatable “Phantom rows”? What are “Lost Updates”? What are different levels of granularity of locking resources? What are different types of Locks in SQL Server? What are different Isolation levels in SQL Server? What are different types of Isolation levels l evels in SQL Server? If you are using COM+ what “Isolation” level is set by default? What are “Lock” hints? What is a “Deadlock” ? What are the steps you can take to avoid “Deadlocks” ? How can I know what locks are running on which resource?


Pooling  Improving Performance with Connection Pooling 

Opening a connection is a database-intensive database-intensive task. It can be one of the slowest operations that you perform in an ASP ASP.NET .NET page. Furthermore, a database has a limited supply of connections, and each connection requires a certain amount of memory overhead (approximately 40 kilobytes per connection). If you plan to have hundreds of users hitting your Web site simultaneously, the process of opening a database connection for each user can have a severe impact on the performance of your Web site. Fortunately, you can safely ignore these bad warnings if you take advantage of connection pooling. When database connections are pooled, a set of connections is kept open so that they can be shared among multiple users. When you request a new connection, an active connection is removed from the pool. When you close the connection, the connection is placed back in the pool. Connection pooling of pooling is connection enabled forpooling, both OleDb connections default. To take advantage you and mustSqlClient be careful to do two by things in your ASP.NET pages. First, you must be careful to use the same exact connection string whenever you open a database connection. Only those connections opened with the same connection string can be placed in the same connection pool. For this reason you should place your connection string in the web.config file and retrieve it from this file whenever you need to open a connection To take advantage of connection pooling pooling in your ASP.NET pages, you also must be careful to explicitly close whatever connection you open as quickly as possible. If you do not explicitly close a connection with the Close() method, the connection is never added back to the connection pool. connection pooling options options that you can add to the SQL Server  connection string: •

<!--[if !supportLists]--><!--[endif]-->Connection Lifetime— Destroys a connection after a certain number of seconds. The default value is 0, which indicates that connections should never be destroyed.

<!--[if !supportLists]-->Connection Reset— Indicates whether connections should be reset when they are returned to the pool. The default value is true.

<!--[if !supportLists]-->Enlist— !supportLists]-->Enlist— Indicates whether a connection should be automatically enlisted in the current transaction context. The default value is true.

<!--[if !supportLists]-->Max Pool Size— The maximum number of connections allowed in a single connection pool. The default value is 100.

<!--[if !supportLists]--><!--[endif]-->Min Pool Size— The minimum number of connections allowed in a single connection pool. The default value is 0.

<!--[if !supportLists]-->Pooling— Determines whether connection pooling is enabled or disabled. The default value is true.

Strongly Typed Dataset Object  Object 

Strongly typed Dataset object allows you to create early-bound data retrieval expression.  Advantage of Strongly Typed dataset 

It is faster than late-bound data retrieval expression.

Its column name is shown in intellisense as you type code.

Difference between Dataset and DataReader : Points to be consider while choosing between the DataSet and DataReader objects  objects  DataSet object

DataReader object

Read/Write access

Read-only access


Supp Supports orts multiple multiple tables tables from differe different nt databases databases

Support Sup ports s a single table based based on a single single SQL query of one database

Disconnected mode

Connected mode

Bind to multiple controls

Bind to a single control

Forw Fo rwar ard d and and back backwa ward rd sca scann nnin ing g of da data ta Slower access to data

Forw Fo rwar ardd-on only ly sca scann nnin ing g of da data ta Faster access to data

Greater overhead to enable enable additional additional features features Lightweight object with very little overhead overhead Supported by Visual Studio .NET tools

Must be manually coded

SQL Injection Problem 

SQL injection is a strategy for attacking databases. Example1:

An ASP page asks the user for a name and a password, and then sends the following string to the database: SELECT FROM users WHERE username = 'whatever' AND password = 'mypassword' It seems safe, but it isn't. A user might enter something like this as her user name: ' OR 1>0 -When this is plugged into the SQL statement, the result looks like this: SELECT FROM users WHERE username = '' OR 1>0 -- AND password = '' This injection comments out the password portion of the statement. It results in a list of all the names in the users table, so any user could get into your system. system. <!--[if !supportLineBreakNewLine]--> <!--[endif]--> The easiest way to prevent this sort of injection is to parse the SQL string and remove any occurrences of "--" before passing the statement. Example 2:

You also have to beware of injections that contain semicolons because semicolons delimit SQL statements. Think about the implications of a user name like this: ' OR 1>0 ; DELETE Customers ; -There are numerous ways a malicious user might penetrate your system using SQL injection and various defenses, but the simplest approach is to avoid dynamic SQL. Instead, use stored procedures everywhere. Thanks to the way SQL passes parameters, injections such as those above will produce errors, and the stored procedure will not execute.

Explain DataView 

It provides a means to filter and sort data within a data table. Example: DataView myDataView = new DataView(myDataSet.Tables["Customers"] DataView(myDataSet.Tables["Customers"]); );

 // Sort the view based on the FirstName column myDataView.Sortt = "CustomerID myDataView.Sor "CustomerID"; ";

 // Filter the dataview to only show customers with the CustomerID of ALFKI myDataView.RowFilter myDataView.Ro wFilter = "CustomerID='ALFKI'"; "CustomerID='ALFKI'";


Explain DataAdapter Object 

It populates dataset from data source. It contains a reference to the connection object and opens and closes the connection automatically when reading from or writing to the database.

Example: SqlDataAdapter daEmp = new SqlDataAdapte SqlDataAdapter( r( "select EmpID, EmpName, Salary from Employees" Employees",, conn);

Fill Method

It is used to populate dataset. example: daEmp.Fill(dsEmp,"Employee");

Update Method

It is used to update database. example: daEmp.Update(dsEmp,"Employee"); Explain DataSet Object  Object 

Dataset is a disconnected, disconnected, in-memory representation of data. It can contain multiple data table from different database.

They contain multiple Datatable objects, which contain columns and rows, just like normal data base tables. You can even define relations between tables to create parent-child relationships.

Example DataSet dsEmp = new DataSet();

For more understanding look for DataAdapter Object Explain DataReader Object  Object 

It provides a forward-only, read-only, connected recordset.

It is most efficient to use when data need not to be updated, and requires forward only traverse. In other words, it is the fastest method to read data.

Example: 1. Fillin Filling g dropd dropdown ownlist listbox box.. 2. Comp Comparing aring username username and password password in databa database. se. SqlDataReader rdr = cmd.ExecuteReader();  //Reading data


while (rdr.Read()) (rdr.Read()) {  //Display data string contact = (string)rd (string)rdr["ContactN r["ContactName"]; ame"]; string company = (string)rdr["CompanyName"]; string city = (string)rdr["City" (string)rdr["City"]; ]; } Object   What is Command Object

It allows to manipulate database by executing stored procedure or sql statements.

A SqlCommand object allows you to specify what type of interaction you want to perform with a data base.

For example, you can do select, insert, modify, and delete commands on rows of data in a data base table. SqlCommand cmd = new SqlCommand("select * from Employees", conn); Object   What is Connection Object

It establishes connection connection.. The connection helps identify the data base server, the data base name, user name, password, and other parameters that are required for connecting to the data base.

Example: SqlConnection conn = new SqlConnection( "Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI"); Provider  What is Data Provider 

A set of libraries that is used to communicate with data source. Eg: SQL data provider for SQL, Oracle data provider for Oracle, OLE DB data provider for access, excel or mysql. What is Data Source  Source 

It can be a database, text file, excel spread sheet or an XML file. Objects  Name ADO.NET Objects 

1. Conn Connec ecti tion on Ob Obje ject ct 2. Comm Comman and d Ob Obje ject ct 3. Da Data taRe Read ader er O Obj bjec ectt 4. Da Data taSe Sett Ob Obje ject ct 5. Da Data taAd Adap apte terr Ob Obje ject ct Recordset   Difference between ADO.net Dataset and ADO Recordset

A DataSet can represent an entire relational database in memory, complete with tables, relations, and


views. · A DataSet is designed to work without any continuing connection connection to the original data source. · Data in a DataSet is bulk-loaded, rather than being loaded on demand. · There's no concept of cursor types in a DataSet. · DataSets have no current record pointer You can use For Each loops to move through the data. · You can store many edits in a DataSet, and write them to the original data source in a single operation. · Though the DataSet is i s universal, other objects in ADO.NET come in different versions for different data sources. Difference between ADO and ADO.net ADO.net  

1. ADO used connected data usage, while ADO.net used disconnected data environmen environment. t. 2. ADO used OLE DB to access data and is COM-based, while ADO.net uses XML as the format for transmitting data to and from your database and web application. 3. In ADO, Record set, is like l ike a single table or query result, while in ADO.net Dataset, can contain multiple tables from any data source. 4. In ADO, it is i s sometime problematic because firewall prohibits prohibits many types of request, while in ADO.net there is no such problem because XML is completely firewall-proof. What is ADO.net  ADO.net 

ADO.net is data access architecture for the Microsoft .NET Framework. ADO.NET is an object-oriented set of libraries l ibraries that allows you to interact with data sources. Commonly, Commonly, the data source is a data base, but it could also be a text file, an Excel spread sheet, or an XML file. connection   Connection Open Error : SQLDataReader makes exclusive use of connection

The SQLDataReader object makes exclusive exclusive use of its SQLConnection object as long as it is open. You are not able to execute any other SqlCommand objects on that connection as long as the SQLDataReader object is open. Therefore, you should always call SQLDataReader SQLDataReader.close() .close() as soon as you are done retrieving data. Subscribe to:  to: Posts (Atom) (Atom)   Most Recent Post • • • • •

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