Data Base Management System

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DATA BASE MANAGEMENT SYSTEM
Meaning of Data baseA database is an organized collection of facts. In other words it is collection of information arranged and presented to serve an assigned purpose. An example of data base is a dictionary, where words are arranged alphabetically. Another example is a telephone directory, where subscriber names are listed in an alphabetical order. Similarly a box of cards with names and addresses written as mailing list, then the box and its contents form a mailing database. The collection of these cards will de termed as database. In order to keep database updated we may need to perform the operations like adding, removing, editing information, etc. In case of telephone diary where we note down the names, address, and phone numbers of our friends. This is also a type if database. When we make our new friends and add the information about them in our diary, it is equivalent to the adding data to the database. If address of our friend changes and we note new address in our diary, it is editing a database. If we want to send a letter to our friend then we look into the diary to locate the address, it is searching a database. In case of telephone diary contains a very large number of names, addresses, and phone numbers. Moreover, the names are not arranged in any order. Thus it would be very difficult to locate the names, address, and phone numbers of our friends. Thus it is essential to arrange the names in some order, say alphabetically, to make the search easy. If the number of friends gets larger, managing the database manually becomes difficult. A database management software package is a helpful tool in such a situation. Any organization, bank, manufacturing company, hospital, university, requires huge amount of data in some or the other form. All such organizations needs to collect data, manipulate them and store them for future use. All such type of organizations requires data for number of purposes like; 1. Preparing sales report , 2. Forecasting sales, 3. Preparing accounts reports, 4. Getting medical histories of patients.

Thus we can say data are very vital corporate resources. The amount of data used these days in organizations can be measured in the range of some billions of bytes or characters. The financial statement involved is also very high. Many organizations have become critically dependent on the continued and successful operations of database.

THE DATABASE APPROACH TO DATA MANAGEMENT
Database technology cuts through many of the problems of traditional file organization. A more rigorous definition of a database is a collection of data organized to serve many applications efficiently by centralizing the data and controlling redundant data. Rather than storing data in separate files for each application, data are stored so as to appear to users as being stored in only one location. A single database services multiple applications. For example, instead of a corporation storing employee data in separate information systems and separate files for personnel, payroll, and benefits, the corporation could create a single common human resources database.

DATA MANAGEMENT SYSTEM
A database management system (DBMS) is software that permits an organization to centralize data, manage them efficiently, and provide access to the stored data by application programs. The DBMS acts as an interface between application programs and the physical data files. When the application program calls for a data item, such as gross pay, the DBMS finds this item in the database and presents it to the application program. Using traditional data files, the programmer would have to specify the size and format of each data element used in the program and then tell the computer where they were located. The DBMS relieves the programmer or end user from the task of understanding where and how the data are actually stored by separating the logical and physical views of the data. The logical view presents data as they would be perceived by end users or

business specialists, whereas the physical view shows how data are actually organized and structured on physical storage media. The database management software makes the physical database available for different logical views required by users. For example, for the human resources database illustrated in Figure 1-3, a benefits specialist might require a view consisting of the employee's name, social security number, and health insurance coverage. A payroll department member might need data such as the employee's name, social security number, gross pay, and net pay. The data for all these views are stored in a single database, where they can be more easily managed by the organization.

ORGANIZING DATA IN A TRADITIONAL FILE ENVIRONMENT
An effective information system provides users with accurate, timely, and relevant information. Accurate information is free of errors. Information is timely when it is available to decision makers when it is needed. Information is relevant when it is useful and appropriate for the types of work and decisions that require it.

You might be surprised to learn that many businesses don't have timely, accurate, or relevant information because the data in their information systems have been poorly organized and maintained. That's why data management is so essential. To understand the problem, let's look how information systems arrange data in computer files and traditional methods of file management.

Draw backs of file system:1. Data excess (redundancy) ± Same information was stored into the several files. A customer has 5 different A/C¶s in bank so its name and other details were stored into all those files. Due to the redundancy memory requirement was bigger and also accessing cost was high. 2. InconsistencyInconsistency problem is totally depended on redundancy (like a bank customer is girl and after marriage she has got a new name and this modifications done in all A/C¶s of bank and their relevant files but mistakenly is any file is left so at the time of accessing this left file will be treated as different customer with comparison to rest to the files.) 3. Difficulty in accessing dataSo many times we have to find a record or list as per the given condition (like those customers. But at the development time of application programmes there was no such concept, so programmer has to develop a new application programme. Now again we want to see the list of all those customer who have balance of less than500 Rs. so again programmer has to develop new application programme for this condition. It has very inconvenient process of accessing data. 4. Security problemEvery user has to use particular portion or part of database according to his/ her need in DBMS so there is some sort of security is provided to restrict each user. But in

file system every user has a separate security file and number of users are more then number of security files is more so it is very inconvenient process. ---------------------------------------------------------------------------------------------------------------------

Difference between file system management v/s Data base management

Topic

File management

Data base management

Data redundancy

May have a high degree of data redundancy

Has a low degree if the database was well designed.

Application maintenance

Low degree of data independence mean higher maintenance cost due to a data file reorganization.

high data independence reduce maintenance cost due to a database reorganization

Data relationship

Handed by application if at all

Al integral parts of DBMS. Provided by DBMS

Integrity control

Usually provide by the programmer if at all

HOW A DBMS SOLVES THE PROBLEMS OF THE TRADITIONAL FILE ENVIRONMENT
A DBMS reduces data redundancy and inconsistency by minimizing isolated files in which the same data are repeated. The DBMS may not enable the organization to

eliminate data redundancy entirely, but it can help control redundancy. Even if the organization maintains some redundant data, using a DBMS eliminates data inconsistency because the DBMS can help the organization ensure that every occurrence of redundant data has the same values. The DBMS uncouples programs and data, enabling data to stand on their own. Access and availability of information will be increased and program development and maintenance costs reduced because users and programmers can perform ad hoc queries of data in the database. The DBMS enables the organization to centrally manage data, their use, and security

MAJOR TYPES OF DATA BASE USED BY THE ORGANIZATION
1. Common operational database: These database store detailed data needed to support the operations of the entire organization. They also may be called subject area database, transaction database, accounting database. Ex. Customer database, personnel database. 2. Common end user database: These database store data and information extracted from selected operational and external database. They consist of summarized data and information most needed by the organization managers and other end users. They are also called information database and management data bases and accessed by executive and user as part of decision support managerial decision making. 3. Distributed databases: These are databases of local work groups and departments at regional office, branch offices manufacturing plant and other work sites. These databases can include segments of both common operational and common user databases, as well as generated and used at a user¶s own site. 4. Personal end users databases: This database consists of a variety of data files developed by end users at their workstations. User may have their own electronic copies of documents they generate with word processing packages or received by electronic mail, from electronic spreadsheets and microcomputer DBMS packages. External database: These can be accessed from large, privately owned data bases or databanks available for a fee to end users and organization from commercial

information service networks. Data is available in the form of statistics on economic and demographic activities from statistical data banks; abstracts from hundreds of newspapers, magazines, and other periodical from bibliographic data banks.

DESIGNING DATABASE
To create a database, you must understand the relationships among the data, the type of data that will be maintained in the database, how the data will be used, and how the organization will need to change to manage data from a company-wide perspective. The database requires both a conceptual design and a physical design. The conceptual, or logical, design of a database is an abstract model of the database from a business perspective, whereas the physical design shows how the database is actually arranged on direct-access storage devices.

DATABASE PROCESSING SYSTEM
Database processing is the proper handling of facts to make them information so that the decisions can be taken.

RECORDING DATA

CLASSIFING DATA

SORTING DATA

STORING DATA

CALCULATING DATA

COMMUNICATING AND INFORMATION OUTPUT

DECISION AND ACTION

---------------------------------------------------------------------------------------------------Characteristics of DBMS
1. DBMS has the capacity to store large amount o data necessary for user s needs. They are stored on direct accessible devices. 2. It has capacity to interrogating data files, retrieving, and modifying data and recording the changes. 3. The data are combined to form operational units to minimize the duplication of data and increase access to al data in the database. 4. The control in the system limit access to the database and builds the confidentially of data in the data base. 5. The advancement in the database enables to add more data and program to the system. 6. DBMS has the capacity to store large amount o data necessary for user s needs. They are stored on direct accessible devices. 7. It has capacity to interrogating data files, retrieving, and modifying data and recording the changes. 8. The data are combined to form operational units to minimize the duplication of data and increase access to al data in the database. 9. The control in the system limit access to the database and builds the confidentially of data in the data base. 10. The advancement in the database enables to add more data and program to the system.

Objectives of data base management system
The main goal of an organizational data base system is to collect the data .The objectives of data base management system are to facilitate the creation of data structure and relieve the programmer of the problems of setting up complicated files. The objectives can be narrated as follows:

1. Eliminate redundant data. 2. Make access to the data easy for the user. 3. Provide for the mass storage of relevant data. 4. Protect the data from physical harm and unauthorized system. 5. Allow for growth in the data base system. 6. Make the latest modifications in the data base available immediately. 7. Allow for multiple users to be active at one time. 8. Provide prompt response to user request for data. 9. Complexity of an organization information system is reduced through centralization of data management.

ARCHITECTURE OF DBMS
The architecture of DBMS is involved in providing a basic framework, which is proposed as standard by ANSI (American National Standard Institute). This is a logical structure, so that one can easily understand the working of the DBMS. It is divided into 3 general levels namely:-

i. ii. iii.

Internal level Conceptual level External level

The following figure illustrates these levels;

External lev

External level (Individual level)

Conceptual level (Community user¶s level)

Internal level (Storage level)

i.

INTERNAL LEVEL ± It is the level which is closest to the physical storage. This level is lowest in hierarchy, but is the basis for all other levels. This level is concerned about the way, in which the data is stored.

ii.

EXTERNAL LEVEL ± This level is the level which is closest to the users. This level can be taken as an interface to the users. This level is highest level and is concerned about how the day is viewed by the users. It is that level which determines the way the data is presented to the users.

iii.

CONCEPTUAL LEVEL ± This level acts as an via media between the internal level and external level by linking them. This level is the one which gives the abstract of the entire database, out of which the necessary data can be taken by external level. It acts as a base from where all other users have the view of data, therefore it is also called as community user view.

COMPONENTS OF DBMS
1. Data (Database) 2. Software 3. Hardwares 4. Users.

The above four components make up the database management system. Each and every component has its own importance and role to play in database management.

1. DATA (DATABASE) ±
This refers to the collection of related data, combined to be stored, at a central place, which is the basis for any activity in the organization. It is that component, for whose management, the DBMS works. This component is very essential and important, as it is the core of any organization and its activity.

2. SOFTWARE ±
This component includes both the system software and all other supporting application softwares, which are used to work on the database. This component is the set of instructions required to manage, maintain and work with data.

3. HARDWARES ±
This includes, the CPU and all other peripheral devices like monitor, keyboard, printer, mouse etc., which are essential for keying in data and giving output, as well the hard disk for storing the data.

4. USERS ±
This component include all types of users, who derive the benefit of getting the work done by the DBMS, so that they have the required data and information with them for decision making.

OBJECT-ORIENTED DATABASE MANAGEMENT SYSTEM

An object database (also object-oriented database management system) is a database management system in which information is represented in the form of objects as used in object-oriented programming.

OR

An object-oriented database management system (OODBMS), sometimes shortened to ODBMS for object database management system), is a database management system (DBMS) that supports the modelling and creation of data as objects.

PROMISES OF OBJECT ORIENTED SYSTEMS
Object-oriented systems make these promises:

Reduced maintenance The primary goal of object-oriented development is the assurance that the system will enjoy a longer life while having far smaller maintenance costs. Because most of the processes within the system are encapsulated, the behaviours may be reused and incorporated into new behaviours.

Real-world modelling Object-oriented systems tend to model the real world in a more complete fashion than

do traditional methods. Objects are organised into classes of objects, and, objects are associated with behaviours. The model is based on objects rather than on data and processing.

Improved reliability Object-oriented systems promise to be far more reliable than traditional systems, primarily because new behaviours can be built from existing objects.

High code reusability When a new object is created, it will automatically inherit the data attributes and characteristics of the class from which it was spawned. The new object will also inherit the data and behaviours from all super classes in which it participates.

ADVANTAGES OF OBJECT ORIENTED DATABASES
Object- oriented databases also offer many of the benefits that were formerly found only in expert systems. With an object- oriented database, the relationships between objects and the constraints in objects are maintained by the database management system, that is, the object themselves. The rules associated with the expert system are essentially replaced by the object schema and the methods. As many expert systems currently do not have adequate database support, object-oriented databases afford the possibility of offering expert system functionality with much better performance. Object-oriented databases offer benefits over current hierarchical and relational database models. They enable support of complex applications not supported well by the other models. They enable programmability and performance, improve navigational access, and simplify concurrency control. They lower the risks associated with referential integrity, and they provide a better user metaphor than the relational model. Object-oriented databases by definition allow the inclusion of more of the code (i.e. the object's methods) in the database itself. This incremental knowledge about the application has a number of potential benefits of the database system itself, including the ability to optimize query processing and to control the concurrent execution of transactions.

Performance, always a significant issue in system implementation, may be significantly improved by using an object-oriented model instead of a relational model. The greatest improvement can be expected in applications with high data complexity and large numbers of inter-relationships. Clustering, or locating the related objects in close proximity, can be accomplished through the class hierarchy or by other interrelations. Caching, or the retention of certain objects in memory or storage, can be optimised by anticipating that the user or application may retrieve a particular instance of the class. When there is high data complexity, clustering and caching techniques in object databases gain tremendous performance benefits that relational databases, because of their fundamental architecture, will never be able to approach. Object-oriented databases can store not only complex application components but also larger structures. Although relational systems can support a large number of tuples (i.e., rows in a table), individual types are limited in size. Object-oriented databases with large objects do not suffer performance degradation because the objects do not need to be broken apart and reassembled by applications, regardless of the complexity of the properties of the application objects. Since objects contain direct references to other objects, complex data set can be efficiently assembled using these direct references. The ability to search by direct references significantly improves navigational access. In contrast, complex data sets in relational databases must be assembled by the application program using the slow process of joining tables. For the programmer, one of the challenges in building a database is the data manipulation language (DML) of the database. DMLs for relational databases usually differ from the programming language used to construct the rest of the application. This contrast is due to differences in the programming paradigms and mismatches of type systems. The programmer must learn two languages, two tool sets, and two paradigms because neither alone has the functionality to build an entire application. Certain types of programming tools, such as application generators and fourth-generation languages (4GLs) have emerged to produce code for the entire application, thereby bridging the mismatch between the programming language and the DML, but most of these tools compromise the application programming process. With object-oriented databases much of this problem is eliminated. The DML can be extended so that more of the application can be written in the DML. Or an objectoriented application language, of example C++ can be extended to be the DML. More or the application can be built into the database itself. Movement across the programming interface between the database the application then occurs in a single paradigm with a

common set of tools. Class libraries can also assist the programmer in speeding the creation of databases. Class libraries encourage reuse of existing code and help minimise the cost of later modifications. Programming is easier because the data structures model the problem more closely. Having the data and procedures encapsulated in a single object makes it less likely that a change to one object will affect the integrity of other objects in the database. Concurrency control is also simplified with an object-oriented database. In a relational database, the application needs to look each record in each table explicitly because related data re-represented across a number of tables. Integrity, a key requirement for databases, can be better supported with an object-oriented database, because the application can lock all the relevant data in one operation. Referential integrity is better supported in an object-oriented database because the pointers are maintained and updated by the database itself. Finally, objectoriented databases offer a better user metaphor than relational databases. The tuple or table, although enabling a well-defined implementation strategy, is not an intuitive modeling framework, especially outside the domain of numbers. Objects offer a more natural and encompassing modeling metaphor.

DIFFERENCE BETWEEN RDBMS AND OODBMS
RDBMSs were never designed to allow for the nested structure. These types of applications are extensively found in CAD/CAE, aerospace, etc. OODBM can easily support these applications. Moreover, it is much easier and natural to navigate through these complex structures in form of objects that model the real world in OODBMS rather than table, tuples and records in RDBMS. It is hard to confuse a relational database with an object-oriented database. The normalised relational model is based on a fairly elegant mathematical theory. Relational databases derive a virtual structure at run time based on values from sets of data stored in tables. Database construct views of the data by selecting data from multiple tables and loading it into a single table (OODBs traverse the data from object to object). Relational databases have a limited number of simple, built-in data types, such as integer and string, and a limited number of built-in operations that can handle these data types. You can create complex data types in a relational database, but you must do it on a linear basis, such as combining fields into records. And the operations on these new complex types are restricted, again, to these defined for the basic types (as opposed to arbitrary data types or sub-classing with inheritance as found in OODBs). The object model supports browsing of object class libraries, which allows the reuse,

rather than the reinvention, of commonly used data elements. Objects in an OODB survive multiple sessions; they are persistent. If you delete an object stored in a relational database, other objects may be left with references to the deleted one and may now be incorrect. The integrity of the data thus becomes suspect and creates inconsistent versions. In the relational database, complex objects must be broken up and stored in separate tables. This can only be done in a sequential procedure with the next retrieval replying on the outcome of the previous. The relational database does not understand a global request and thus cannot optimise multiple requests. OODBs can issue a single message (request) that contains multiple transactions. The relational model, however, suffers at least one major disadvantage. It is difficult to express the semantics of complex objects with only a table model for data storage. Although relational databases are adequate for accounting or other typical transactionprocessing applications where the data types are simple and few in number, the relational model offers limited help when data types become numerous and complex. Object-oriented databases are favoured for applications where the relationships among elements in the database carry the key information. Relational databases are favoured when the values of the database elements carry the key information. That is, objectoriented models capture the structure of the data; relational models organise the data itself. If a record can be understood in isolation, then the relational database is probably suitable. If a record makes sense only in the context of other records, then an objectoriented database is more appropriate.

Engineering and technical applications were the first applications to require databases that handle complex data types and capture the structure of the data. Applications such as mechanical and electrical computer-aided design (MCAD and ECAD) have always used nontraditional forms of data, representing such phenomena as three-dimensional images and VLSI circuit designs. Currently these application programs store their data in application-specific file structures. The data - intensiveness of these applications is not only in the large amount of data that need to be programmed into the database, but also in the complexity of the data itself. In these design-based applications, relationships among elements in the database carry key information for the user. Functional requirements for complex cross references, structural dependences, and version management all require a richer representation than what is provided by hierarchical or relational databases.

ADVANTAGES OF DBMS

DBMS (Database Management System) is preferred ever the conventional file processing system due to the following advantages: 1. Controlling Data Redundancy-In the conventional file processing system, every user group maintains its own files for handling its data files. This may lead to ‡ Duplication of same data in different files. ‡ Wastage of storage space, since duplicated data is stored. ‡ Errors may be generated due to updation of the same data in different files. ‡ Time in entering data again and again is wasted. ‡ Computer Resources are needlessly used. ‡ It is very difficult to combine information. 2. Elimination of Inconsistency - In the file processing system information is duplicated throughout the system. So changes made in one file may be necessary be carried over to another file. This may lead to inconsistent data. So we need to remove this duplication of data in multiple file to eliminate inconsistency. For example: - Let us consider an example of student's result system. Suppose that in STUDENT file it is indicated that Roll no= 10 has opted for 'Computer'course but in RESULT file it is indicated that 'Roll No. =l 0' has opted for 'Accounts' course. Thus, in this case the two entries for z particular student don't agree with each other. Thus, database is said to be in an inconsistent state. Sc to eliminate this conflicting information we need to centralize the database. On centralizing the data base the duplication will be controlled and hence inconsistency will be removed. Data inconsistency are often encountered in every day life Consider an another example, w have all come across situations when a new address is communicated to an organization that we deal it (Eg - Telecom, Gas Company, Bank). We find that some of the communications from that organization are received at a new address while other continued to be mailed to the old address. So combining all the data in database would involve reduction in redundancy as well as inconsistency so it is likely to reduce the costs for collection storage and updating of Data. Let us again consider the example of Result system. Suppose that a student having Roll

no -201 changes his course from 'Computer' to 'Arts'. The change is made in the SUBJECT file but not in RESULT'S file. This may lead to inconsistency of the data. So we need to centralize the database so that changes once made are reflected to all the tables where a particulars field is stored. Thus the update is brought automatically and is known as propagating updates. 3. Better service to the users - A DBMS is often used to provide better services to the users. In conventional system, availability of information is often poor, since it normally difficult to obtain information that the existing systems were not designed for. Once several conventional systems are combined to form one centralized database, the availability of information and its updateness is likely to improve since the data can now be shared and DBMS makes it easy to respond to anticipated information requests. Centralizing the data in the database also means that user can obtain new and combined information easily that would have been impossible to obtain otherwise. Also use of DBMS should allow users that don't know programming to interact with the data more easily, unlike file processing system where the programmer may need to write new programs to meet every new demand. 4. Flexibility of the System is Improved - Since changes are often necessary to the contents of the data stored in any system, these changes are made more easily in a centralized database than in a conventional system. Applications programs need not to be changed on changing the data in the database. 5. Integrity can be improved - Since data of the organization using database approach is centralized and would be used by a number of users at a time. It is essential to enforce integrity-constraints. In the conventional systems because the data is duplicated in multiple files so updating or changes may sometimes lead to entry of incorrect data in some files where it exists. For example: - The example of result system that we have already discussed. Since multiple files are to maintained, as sometimes you may enter a value for course which may not exist. Suppose course can have values (Computer, Accounts, Economics, and Arts) but we enter a value 'Hindi' for it, so this may lead to an inconsistent data, so lack of Integrity. Even if we centralized the database it may still contain incorrect data. For example: ‡ Salary of full time employ may be entered as Rs. 500 rather than Rs. 5000. ‡ A student may be shown to have borrowed books but has no enrollment. ‡ A list of employee numbers for a given department may include a number of non existent employees. These problems can be avoided by defining the validation procedures whenever any update operation is attempted.

6. Standards can be enforced - Since all access to the database must be through DBMS, so standards are easier to enforce. Standards may relate to the naming of data, format of data, structure of the data etc. Standardizing stored data formats is usually desirable for the purpose of data interchange or migration between systems. 7. Security can be improved - In conventional systems, applications are developed in an adhoc/temporary manner. Often different system of an organization would access different components of the operational data, in such an environment enforcing security can be quiet difficult. Setting up of a database makes it easier to enforce security restrictions since data is now centralized. It is easier to control who has access to what parts of the database. Different checks can be established for each type of access (retrieve, modify, delete etc.) to each piece of information in the database. Consider an Example of banking in which the employee at different levels may be given access to different types of data in the database. A clerk may be given the authority to know only the names of all the customers who have a loan in bank but not the details of each loan the customer may have. It can be accomplished by giving the privileges to each employee. 8. Organization's requirement can be identified - All organizations have sections and departments and each of these units often consider the work of their unit as the most important and therefore consider their need as the most important. Once a database has been setup with centralized control, it will be necessary to identify organization's requirement and to balance the needs of the competating units. So it may become necessary to ignore some requests for information if they conflict with higher priority need of the organization. It is the responsibility of the DBA (Database Administrator) to structure the database system to provide the overall service that is best for an organization. For example: - A DBA must choose best file Structure and access method to give fast response for the high critical applications as compared to less critical applications. 9. Overall cost of developing and maintaining systems is lower - It is much easier to re¬spond to unanticipated requests when data is centralized in a database than when it is stored in a conventional file system. Although the initial cost of setting up of a database can be large, one normal expects the overall cost of setting up of a database, developing and maintaining application programs to be far lower than for similar service using conventional systems, Since the productivity of program¬mers can be higher in using non-procedural languages that have been developed with DBMS than using procedural languages. 10. Data Model must be developed - Perhaps the most important advantage of setting up of database system is the requirement that an overall data model for an organization be build. In conven¬tional systems, it is more likely that files will be designed as per

need of particular applications demand. The overall view is often not considered. Building an overall view of an organization's data is usual cost effective in the long terms. 11. Provides backup and Recovery - Centralizing a database provides the schemes such as recovery and backups from the failures including disk crash, power failures, software errors which may help the database to recover from the inconsistent state to the state that existed prior to the occurrence of the failure, though methods are very complex.

DISADVANTAGES OF DBMS

Danger of a Overkill: For small and simple applications for single users a database system is often not advisable. Complexity: A database system creates additional complexity and requirements. The supply and operation of a database management system with several users and databases is quite costly and demanding. Qualified Personnel: The professional operation of a database system requires appropriately trained staff. Without a qualified database administrator nothing will work for long. Costs: Through the use of a database system new costs are generated for the system itselfs but also for additional hardware and the more complex handling of the system Lower Efficiency: A database system is a multi-use software which is often less efficient than specialised software which is produced and optimised exactly for one problem.
y y y y y

Database systems are complex, difficult, and time-consuming to design Substantial hardware and software start-up costs Damage to database affects virtually all applications programs Extensive conversion costs in moving form a file-based system to a database system Initial training required for all programmers and users

APPLICATIONS OF DBMS Database is widely used all around the world in differnt sectors:
1.Banking: For customer information, accounts loans and banking transactions.

2.Airlines: For reservations and schedule information. Airlines were among the first to use database in a geographically disturbed manner-terminals situated around the world accessed the central database system through phone lines and other data networks. 3.Universities: For student information, course registrations and grades. 4.Credit card transactions: For purchases on credit cards and generation of monthly statements. 5.Telecommunications: For keeping records of calls made, generating monthly bills, maintaining balances on prepaid calling cards and storing information about the communication networks. 6.Finance: For storing information about holdings, sales and purchase of financial instruments such as stocks and bonds. 7.Sales: For customer, product and purchase information. 8.Manufacturing: For management of supply chain and for tracking production of items in factories, inventories of items in warehouses/stores and orders for items. 9.Human Resources: For information about employees, salaries, payroll taxes and benefits and for generation of paychecks. 10.Web based services: For taking web users feedback, responses, resource sharing etc.

CONCLUSION

When the application program calls for a data item, such as gross pay, the DBMS finds this item in the database and presents it to the application program. Using traditional data files, the programmer would have to specify the size and format of each data element used in the program and then tell the computer where they were located. The DBMS relieves the programmer or end user from the task of understanding where and how the data are actually stored by separating the logical and physical views of the data. The logical view presents data as they would be perceived by end users or

business specialists, whereas the physical view shows how data are actually organized and structured on physical storage media. The database management software makes the physical database available for different logical views required by users. The data for all these views are stored in a single database, where they can be more easily managed by the organization.

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