Database Management Systems

1. DatabaseManagement Systems Lecture - 6

2. In Previous Lecture • We were discussing Context Diagram that…..

3. In Previous Lecture • We were discussing Context Diagram that….. • And also the level 0 Diagram which is …..

4. Detailed Diagrams • Show processes in successive levels of detail • shows major sub-processes

5. Detailed Diagrams • Outline numbering • 1.1, 1.2, …, 1.n Level one, shows internal details for each major sub-process • 1.1.1, 1.1.2,…1.1.n Level two

6. Detailed Diagrams • Limit number of process to 7 to 9 per page/diagram for clarity • All elements must be named

7. Detailed Diagrams • All process have both inputs and outputs • Outputs must differ from inputs • Child diagrams and parent process must have same input/output

8. Class Registration C Student Registration S Diagram 0 Class Requests 1.0 Process Requests Old Class Data Student Request Status Updated Class Data Updated Student Data 2.0 Produce Student Schedule 7.0 Produce Faculty Load Sheets 5.0 Produce Class Lists 6.0 Produce Class Counts 3.0 Create Student File 4.0 Create Class File Student Data Faculty member Course Offering Registrar Dean

9. Class Registration C Student Registration S Detailed Diagram Old Class Data Class Requests 1.1 Edit Requests 1.2 Check Class Counts Updated Class Data Student Valid Requests Invalid Request Rejected Request Accepted Request Accepted Request 1.4 Update Class Data 1.3 Update Student Data

10. Data Dictionary A repository of information that describes logical structure of database, or it contains the metadata

11. Data Dictionary • May be integrated or freestanding • Integrated is referred by DBMS • Freestanding as a CASE tool

12. Cross Reference Matrix • A Data Dictionary tool • Used to link different things, like functions to entities, or requirements to attributes • Can be manual even

13. Cross Reference Table

14. Summary • Analyze User Environment or • Preliminary Study + Requirements Analysis • Use of CASE or manual tools

15. Database Design Phase

16. Database Design • Design and Model mean the same • Database Design represents logical structure of the database

17. Database Modeling • Process of creating a logical representation of the structure of the database • The most important task in database development

18. Points to Remember • A database must mirror the real world. Only then can it answer questions about the real world! • The emphasis of data modeling is on representing reality

19. Points to Remember • Ideally it should be a represented graphically • The goal is to identify the facts to be stored in the database • Data modeling involves users and analysts.

20. Data Model • Created using a data model • Data Model: is a set of tools or constructs that is used to construct a database design

21. Significance of DM • Facilitates and provides guidelines or rules in the DB design process • Every DBMS is based on a DM

22. Types of Data Models • Semantic: Entity-Relationship, Object-Oriented • Record based: Hierarchical, Network, Relational

23. DB Design Types • Conceptual: using SDM • Logical: using DM of tool • Physical: using the DBMS

24. DatabaseManagement System Lecture - 6