DB Basic Concepts. Rab Nawaz Jadoon DCS. Assistant Professor. Department of Computer Science. COMSATS IIT, Abbottabad Pakistan

Transcription

1 DB Basic Concepts DCS COMSATS Institute of Information Technology Rab Nawaz Jadoon Assistant Professor COMSATS IIT, Abbottabad Pakistan Management Information Systems (MIS)

2 Database Management System (DBMS) What a DBMS Does History of Database Systems Purposes of a DBMS Components of DBMS Environment Types of Database Users DBMS Components Advantages of DBMS Disadvantages of DBMS World Wide Web Online Transaction Processing (OLTP) Online Analytical Processing (OLAP) Lecture Agenda

3 Database Management System (DBMS) A software system that enables users to define, create, and maintain the database and which provides controlled access to this database. Provides systematic method of creating, updating, storing, and retrieving data in a database It enables end users and application programmers to share data among multiple applications A DBMS also provides facilities for controlling data access, enforcing data integrity, managing concurrency control, and restoring a database.

4 Allows users to store data manage change (updates) organize data retrieve data retain privacy (security) Provides Data Definition Language (DDL) Data Manipulation Language (DML) Data Control Language (DCL) These may be the same language! What a DBMS does?

5 First-generation Hierarchical and Network Second generation Relational Third generation History of Database Systems Extended Relational, Object-Oriented

6 Purposes of a DBMS Access Provide one application to access many databases Layers Hide physical storage considerations from the user Views To provide only the data a user needs Security Restrict access to the data Integrity Preserve data integrity while supporting change Recovery Return the database to a consistent state after a failure of any kind Concurrency Offer simultaneous access to many users Backup

7 Hardware: Components of DBMS Environment Can range from a PC to a network of computers. Software: DBMS, operating system, network software (if necessary) and also the application programs. Data used by the organization and a description of this data (a schema). Procedures: Instructions and rules that should be applied to the design and use of the database and DBMS. People.

8 Data Administrator (DA) DA is responsible for the management of the data resources including database planning, development and maintenance of standards, policies and procedures and conceptual/logical data design. Database Administrator (DBA) DBA is responsible for the physical realization of the database, including physical database design and implementation, security and integrity and maintenance of operational system. Database Designers Logical Database Designer Types of Database Users LDD is concerned with identifying entities, attributes, the relationship between data, and constraints of the data to be stored in the database.

9 Physical Database Designer Types of Database user Is concerned with how logical database is to be physically realized. Database systems programmers writes the DBMS software Applications developers write the client software that allows end users to interface with the DBMS End users use the information provided by the database to achieve a personal or organizational goal

10 Data dictionary DBMS Components stores information about database objects Data dictionary compiler extracts database information and store it in data dictionary Query processor interprets and optimizes user queries Transaction manager communicates with recovery manager and scheduler to ensure data consistency in multi-user environments Storage manager

11 DBMS Components

12 Advantages of DBMS Control of data redundancy. Data consistency More information from the same amount of data. Sharing of data. Improved data integrity. Improved security. Enforcement of standards. Economy of scale. Balanced conflicting requirements Improved data accessibility and responsiveness Increased productivity Improved maintenance through data independence Increased concurrency Improved backup and recovery services

13 Complexity Size Cost of DBMS Additional hardware costs Cost of conversion Performance Higher impact of a failure Disadvantages of DBMS

14 World Wide Web Organizations are now rapidly building new database applications or reengineering existing ones to take full advantage of the web This increases the number of skills that are needed to be a DBA XML documents are used to pass data between different programs on the network XSLT programs are used to translate XML documents into different formats

15 Online Transaction Processing (OLTP) Retrieval, update, or insertion of isolated facts To serve day-to-day business needs Many users, small transactions, highly dynamic data reflecting current situation

16 Online Analytical Processing (OLAP) Exploration of multi-dimensional data To support decision-making and strategic planning Few users, large transactions, static historical data

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