Data Base Management System
Content
By-ouvesh akhtar
The following are examples of database applications: computerized library systems automated banking system flight reservation systems computerized parts inventory systems
Database management system, or DBMS, is a computer software program that is designed as the means of managing all databases that are currently installed on a system hard drive or network. Different types of database management systems exist, with some of them designed for the oversight and proper control of databases that are configured for specific purposes. Here are some examples of the various incarnations of DBMS technology that are currently in use, and some of the basic elements that are part of DBMS software applications.
Primary key
Every entity (unless it is a weak entity) must have a minimal set of uniquely identifying attributes, which is called the entity's primary key
`
Is a combination of one or more columns in a table.
`
Is a combination one or more identifies a record in a table
PURCHASE ID
PURCHASE DATA
ITEM CODE
ITEM CODE
ITEM COST
ITEM QUANTITY
Logical data description refers to the manner in which data viewed by the programmer . the logical data model is conceptual and it reflects the way the user describes the realty.
What is an Entity Entity can be an account, activity, or contact about which data can be stored.
CUSTOMER
GOODS
weak entity is the one that does not exit own its own(depend on other entity) strong entity is the one that is indepenent
What is attribute with respect to DBMS?
An object or entity characterized by its properties or attributes. In relational database systems attributes correspond to fields
PRIMARY KEY NAME
CUSTOMER
GOODS
What Is Relationship In DBMS?
A relationship is an combination (association) among the instance of one or more entity type. That is of interest to the organization
child
child
In many to many relationship, one record in a table can be related to one or more records in a another table
GOODS CUSTOMERS GOODS CUSTOMERS GOODS
3.
Three file in PDC. 1. Sequential files 2. Direct files Indexed sequential files
`
`
The data stored and retrieved in a sequence manner. Generally , these files are stored on sequentail storage devices like magnetic tapes.
`
In direct files , facilitate accessing any record randomly or directly. These files are stored in CDs.
a)
Users-three users involve in DBMS, application
programmers, end users, DBA. Software-software of a data base management system includes the DBMS, OS, network software(if necessary), and the application programs. Hardware-it also includes various storage devices and I/O devices. Data-data stored in a database includes numerical values including whole number and float number and characters, true or false.
b)
c)
d)
Requests for information from a database are made in the form of a query, which is a stylized question. For example, the query SELECT ALL WHERE NAME = "SMITH" AND AGE > 35 requests all records in which the NAME field is SMITH and the AGE field is greater than 35. The set of rules for constructing queries is known as a query language. Different DBMSs support different query languages, although there is a semi-standardized query language called SQL (structured query language). Sophisticated languages for managing database systems are called fourth-generation languages, or 4GLs for short.
The following are examples of database applications: computerized library systems automated banking system flight reservation systems computerized parts inventory systems
Database management system, or DBMS, is a computer software program that is designed as the means of managing all databases that are currently installed on a system hard drive or network. Different types of database management systems exist, with some of them designed for the oversight and proper control of databases that are configured for specific purposes. Here are some examples of the various incarnations of DBMS technology that are currently in use, and some of the basic elements that are part of DBMS software applications.
Primary key
Every entity (unless it is a weak entity) must have a minimal set of uniquely identifying attributes, which is called the entity's primary key
`
Is a combination of one or more columns in a table.
`
Is a combination one or more identifies a record in a table
PURCHASE ID
PURCHASE DATA
ITEM CODE
ITEM CODE
ITEM COST
ITEM QUANTITY
Logical data description refers to the manner in which data viewed by the programmer . the logical data model is conceptual and it reflects the way the user describes the realty.
What is an Entity Entity can be an account, activity, or contact about which data can be stored.
CUSTOMER
GOODS
weak entity is the one that does not exit own its own(depend on other entity) strong entity is the one that is indepenent
What is attribute with respect to DBMS?
An object or entity characterized by its properties or attributes. In relational database systems attributes correspond to fields
PRIMARY KEY NAME
CUSTOMER
GOODS
What Is Relationship In DBMS?
A relationship is an combination (association) among the instance of one or more entity type. That is of interest to the organization
child
child
In many to many relationship, one record in a table can be related to one or more records in a another table
GOODS CUSTOMERS GOODS CUSTOMERS GOODS
3.
Three file in PDC. 1. Sequential files 2. Direct files Indexed sequential files
`
`
The data stored and retrieved in a sequence manner. Generally , these files are stored on sequentail storage devices like magnetic tapes.
`
In direct files , facilitate accessing any record randomly or directly. These files are stored in CDs.
a)
Users-three users involve in DBMS, application
programmers, end users, DBA. Software-software of a data base management system includes the DBMS, OS, network software(if necessary), and the application programs. Hardware-it also includes various storage devices and I/O devices. Data-data stored in a database includes numerical values including whole number and float number and characters, true or false.
b)
c)
d)
Requests for information from a database are made in the form of a query, which is a stylized question. For example, the query SELECT ALL WHERE NAME = "SMITH" AND AGE > 35 requests all records in which the NAME field is SMITH and the AGE field is greater than 35. The set of rules for constructing queries is known as a query language. Different DBMSs support different query languages, although there is a semi-standardized query language called SQL (structured query language). Sophisticated languages for managing database systems are called fourth-generation languages, or 4GLs for short.
