1. File and data base concepts DB design

2. Webcast will cover n Databases n Entities n Basic ERD n PK & FK n Basic Database Design

3. DB: subsystems DB logical structures: hierachical network relational Data Base OSDBM DBMS DDL DML User Application program

4. Views, Schema and Subschemas 2 4 5 7 9 10 12 13 8 15 17 1

5. Types of databases n Hierarchical n Network n Relational n Object-oriented

6. DBMS Has Two Parts n DML: Data Manipulation Language n DDL: Data Definition Language

7. Structured Query Language (SQL) Syntax SELECT col names FROM tablenames WHERE conditions

8. Example Employee nameJob TitleRoom locationExtension Andazola, GenevieveSecretary, Financial Aid1-3082245 Carter, Georgia Secretary, Student Affairs 1-2244716 Durbin,Martina Secretary, Placement Service 1-1104235 Ezikian, Olivia Secretary II,Student Affairs 1-2244714 Hart, Dr. John Director,Placement Services 1-110B4234 Jacobs, Harry M.Director, Financial Aid1-3082244 Jones, Madalena Assistant Director, Student Affairs 1-2244715 Smith, RoseSecretary, Admissions1-1044823 Wells, Dr.Janet Vice-President, Student Affairs 1-2244713 York, RichardDirector, Admissions1-1044822

9. SQL EMPLOYEE (EMPLOYEE_NAME, JOB_TITLE, ROOM_LOCATION, EXTENSION) Ex: get the names of all employees SELECT employe_ename FROM EMPLOYEE; Ex: Get employee information that have location I- 308 Select * FROM EMPLOYEE WHERE ROOM_LOCATION = ‘I-308’;

10. PRIMARY KEY (PK) a unique identifier guarantees that each row of a relation can be uniquely addressed

11. BANK ACCOUNT ( ss#, cust name, cust address) What’s the PK?

12. BANK ACCOUNT( ss#, cuts name, cust address) n SS# can be a PK since it can not repeat in this table What happens if we add cust_account to this table BANK ACCOUNT( ss#, cuts name, cust address, cust-account)

13. n ss# can NOT be a PK if we assume a customer can have multiple accounts For customer smith Table may look like 111-11-1123 smithUBCHK112 111-11-1123 smithUBSAV123 n Note now ss# can NOT be a PK since ss# values are repeating n this violates the definition of PK, it returns two rows!!!!

14. BANK ACCOUNT( ss#, cuts name, cust address, cust-account) n Can cust-account can be a PK? Only if two customers can NOT share the same account, i.e., no joint account

15. BANK ACCOUNT( ss#, cuts name, cust address, cust-account) n PK must be a combination of TWO attributes n In this case SS# and cust-account Should be PK for this relation

16. FK n Relates two tables n Used to maintain INTEGRITY (cross reference) An attribute in ONE table must match values in another table where that attribute is a PK

17. VENDOR and PRODUCT tables VENDOR (Vend_CODE, VEND_CONTACT, VEND_ADDRESS, VEND_PHONE) PRODUCT (PROD_CODE, PROD- DESCRIPTION, PROD_PRICE, PROD_ON_HAND, VEND_CODE) Red implies PK for each table Purple key is PRODUCT table is FK to VENDOR table

18. Entities An object of interest n Person n Place n Event n Concept Ex:StudentOrderCustomer

19. Relationship Exists between entities With entity itself Binary between TWO entities Ternary between THREE entities

20. Relationship among entities Assume: A team can have many players and a player can play for ONLY ONE team TEAM PLAYER TEAM PLAYER TEAM-------  > PLAYER

21. Relationship? STUDENT CLUB Can a student belong to many clubs? Yes then 1:m Can a club have many student members? Yes then 1:n M:N M:N STUDENT CLUB

22. DB Design Concepts ENROLLMENT ( SID, SNAME, SADD,CID,CNAME,GRADE,SEMESTER) how to represent entities and relations

23. 112Smith,JUBINSS640MISSp06 112Smith,JUBINSS651DBMSSp06 112Smith,JUBMGMT600LeadershipSp06 113Mary,KTOWSONINSS640MISSp06 113Mary,KTOWSONMGMT600LeadershipBF05 114Chao, PTOWSONINSS640MISBF05 Data Redundancy

24. Remove redundancy STUDENT (SID,SNAME,SADD) CLASS(CID,CNAME) GRADE (SID,CID,GRADE,SEMESTER )

25. DB Design principles NORMALIZATION: 1. represent each ENTITY as a TABLE 2. select the PRIMARY KEY 3. assign entity ATTRIBUTES to FIELDS 4. represent an ONE-TO-MANY relation by a FOREIGN KEY in the MANY table. 5. represent MANY-TO MANY relations as a NEW TABLE. Use FOREIGN KEYS to identify entities involved. The combination of foreign keys is the PRIMARY KEY of the new table. Assign the common attributes to fields.