04/10/23

1Database

Management Systems

04/10/23

2Data

• Meaningful facts, text, graphics, images, sound, video segments that can be recorded and that have implicit meaning.

• E.g. name, address , city, telephone no of the people

Database• Organized collection of related information structure• It ensures that information is always stored in

keeping with respective fields• E.g. Telephone directory

04/10/23

3

Database Management System (DBMS)• It is the software that defines a database, stores

the data, supports a query language, produces reports and creates data entry screens.

Need of DBMS• Problems with traditional file processing systems:

–Uncontrolled duplication»Wastes space»Hard to update all files

–Inconsistent data–Inflexibility–Limited data sharing–Poor programmer productivity –Excessive program maintenance

• To build a modern business applications

04/10/23

4DBMS Features• Provides a way to structure data as records, tables,

or objects

• Accepts data input from operators and stores that data for later retrieval

• Provides query languages for searching, sorting, reporting, and other "decision support" activities

• Provides multi-user access to data, along with security features that prevent some users from viewing and/or changing certain types of information

04/10/23

5

Advantages of DBMS• Controlling Redundancy

–No need to storing the same data multiple time

• Restricting unauthorized access–E.g. financial data is often considered confidential

• Providing backup and recovery• Providing storage structure for efficient query

processing• Representing complex relationships among data• Reduced application development time• Flexibility• Availability of up-to-date information• Economics of scale

04/10/23

6

Disadvantages of DBMS

• The overhead cost of using DBMS is high due to–High initial investments in hardware, software and training–Overhead for providing security, concurrency control, recovery and integrity factions–Generality that a DBMS provides for defining and processing data

• Data must be carefully organized• Database systems are complex• Problems may arise if database systems

application are not implemented properly

04/10/23

7Applications of DBMS

• Banking: for customers information, accounts, loans and banking transactions

• Airlines: for reservations and schedule information• Universities: for student information, course

registration and grades• Credits and transactions: for purchases on credit

card and generating monthly bills, maintaining balances

• Finance• Sales• Online retailers• Manufacturing• Human resources

04/10/23

8 Types of DBMS

• Hierarchical Database• Network Database• Relational Database• Object-Oriented Database

Hierarchical Database• To store or retrieve data, DBMS starts at the top• Then it store or retrieves all nested data• Relatively fast only if to access data from the top• Difficult to search for the item in the bottom or

middle

04/10/23

9

Network database• Item are physically separated

• Connected by arrows

• Entry points are predefined items that can be searched

• Arrows are to find and display matching data

• Cost is high

Relational database• E.F. Codd originated the relational database approach in

1970

• Data are stored in separate sets of data like tables

• Each table stores data in columns

• Tables are not physically connected

• Instead data is linked between columns

• Flexible and efficient

04/10/23

10 Object oriented database• The goal is to define objects that can be reused in

many programs• An object has three components: a name, a set of

properties and a set of methods or functions• Base objects are same as those of relational• New objects can be defined in terms of existing

objects• Saving time & reduce error• Transferring complex objects like images and video

can be challenging or impossible for different types of hardware

Life cycle of Database System Development

04/10/23

11

Application programs/ Queries

DBMS software

Database System

Software to process Queries/Programs

Users /programmers

Software to access stored data

Stored database definition (meta data) Stored database

Database system environment

Components of DBMS: (functions)

04/10/23

12 Data Definition

The DBMS provides functions to define the structure of the data in the application. These include defining and modifying the record structure, the type and size of fields and the various constraints/conditions to be satisfied by the data in each field.

Components of DBMS: (functions)

04/10/23

13

Data Manipulation

Once the data structure is defined, data needs to be inserted, modified or deleted. The functions which perform these operations are also part of the DBMS.

04/10/23

14

Data Security & Integrity

The DBMS contains functions which handle the security and integrity of data in the application. These can be easily invoked by the application and hence the application programmer need not code these functions in his/her programs.

Data Recovery & Concurrency

Recovery of data after a system failure and concurrent access of records by multiple users are also handled by the DBMS.

04/10/23

15

Data Dictionary Maintenance

Maintaining the Data Dictionary which contains the data definition of the application is also one of the functions of a DBMS.

Performance

Optimizing the performance of the queries is one of the important functions of a DBMS. Hence the DBMS has a set of programs forming the Query Optimizer which evaluates the different implementations of a query and chooses the best among them.

Database Users

04/10/23

16Database administratorsDatabase administrators responsible for authorizing access to the responsible for authorizing access to the

database, for co-ordinating and monitoring its database, for co-ordinating and monitoring its use, acquiring software, and hardware use, acquiring software, and hardware resources, controlling its use and monitoring resources, controlling its use and monitoring efficiency of operations.efficiency of operations.

Database DesignersDatabase Designers responsible to define the content, the structure, responsible to define the content, the structure,

the constraints, and functions or transactions the constraints, and functions or transactions against the database. They must communicate against the database. They must communicate with the end-users and understand their needs.with the end-users and understand their needs.

End-usersEnd-users They use the data for queries, reports and some They use the data for queries, reports and some

of them actually update the database content.of them actually update the database content.

04/10/23

17

Users are differentiated by the way they expect to interact with the system

Application programmers – interact with system through DML calls

Sophisticated users – form requests in a database query language

Specialized users – write specialized database applications that do not fit into the traditional data processing framework

Naive users – invoke one of the permanent application programs that have been written previously– Examples, people accessing database over the

web, bank tellers, clerical staff

04/10/23

18

THANK YOU