Lesson01 Database introduction
- 1. Syed M Irteza 1 Lesson 01 Database Systems
- 2. Syed M Irteza 2 Introduction To Course ïŻ Pre-Requisite: None ïŻ Textbook: An Introduction To Database Systems. by C.J. Date. 8th Edition.
- 3. Syed M Irteza 3 Overview of DBMS ïŻ What is it? A computer system which provides mechanisms to store, retrieve and manipulate information in a manner which is both efficient and safe. ïŻ or A computerized system whose overall purpose is to maintain information and to make that information available on demand.
- 4. Syed M Irteza 4 Overview of DBMS ïŻ Why is it necessary? To provide a level of abstraction, control and functionality between the data and the user(s) that is not possible using a collection of conventional electronic files.
- 5. Syed M Irteza 5 DBMS Application Program Application Program DB User1 User2 Front End Back End
- 6. Syed M Irteza 6 DBMS cont. ïŻ Front End (Clientâs Part) ïź Provides user interfaces, e.g Developer 2000 for oracle, or other user applications. ïź Visual Basic, MS Access. ïŻ Back End (Server Part) ïź Provides the database, etc. ïź Access, Paradox, MySQL, Oracle, DB2, SQL Server, Sybase, Cloudscape.
- 7. Syed M Irteza 7 File Processing Systems ïŻ Problems associated with a collection of files ïź redundancy ïź inconsistency ïź integrity ïź integration ïź atomicity ïź security
- 8. Syed M Irteza 8 DBMS vs. File Processing Systems ïŻ Major Difference: ïź FPS ïŻ A partition, localized control based on administrative units. ïź DBMS ïŻ A unified centralized control under DBA(database administrator).
- 9. Syed M Irteza 9 FPS Personnel File Sales File Application Program Application Program Personnel Department Sales Department ? ? ? ? ? ? ?
- 10. Syed M Irteza 10 FPS cont. ïŻ They build their own files and application programs, in languages like COBOL etc. ïŻ Control is Localized. ïŻ May not be compatible with each other ïź E.g. one use C++ and second use COBOL ïź Results in a lot of over head in making the both compatible and a lot of troubles.
- 11. Syed M Irteza 11 DBMS ïŻ In a DBMS everything is under one roof. And the DBA has complete control over the entire database. ïŻ Control is centralized.
- 12. Syed M Irteza 12 Benefits Of DBMS âą Data Sharing among different users is possible. Information is in a Table usually Sales Employee
- 13. Syed M Irteza 13 Benefits Of DBMS cont. ïŻ Data Redundancy is Reduced. ïŻ Data Inconsistency is reduced, easier to update. ïź In FPS we have to change every entry in every file with the same data. ïź In DBMS redundancy is reduced so only very rare data inconsistency. Usually only one record In DBMS.
- 14. Syed M Irteza 14 Benefits Of DBMS cont. ïŻ Standards can be enforced. ïź Practically desirable for data interchange over wide area. ïź So we can enforce special formats for tables , so data can be handled and processed. NY Lahore London Chicago Paris
- 15. Syed M Irteza 15 Benefits Of DBMS cont. ïŻ Security ïź The DBA can ensure proper access to the database in FPS , it is difficult to maintain security for dozens of diff. Departments. ïź In DBA we can impose total security. Sales Management H.R
- 16. Syed M Irteza 16 Benefits Of DBMS cont. ïŻ Transaction Support ïŻ Integrity Support
- 17. Syed M Irteza 17 Tables Used S# SNAME STATUS CITY S1 Smith 20 London S2 Jones 10 Paris S3 Blake 30 Paris S4 Clark 20 London S5 Adams 30 Athens Supplier S P# PNAME COLOR WEIGHT CITY P1 Nut Red 12 London P2 Bolt Green 17 Paris P3 Screw Blue 17 Rome P4 Screw Red 14 London P5 Cam Blue 12 Paris P6 Cog Red 19 London Parts P S# P# QTY S1 P1 300 S1 P2 200 S1 P3 400 S1 P4 200 S1 P5 100 S1 P6 100 S2 P1 300 S2 P2 400 S3 P2 200 S4 P2 200 S4 P4 300 S4 P5 400 Supplier & Parts SP
- 18. Syed M Irteza 18 End END OF LESSON 01 (These slides were taken from M A Shahid)