Relational Database Schema normalizer

1. Relational Database Schema normalizer P03 A0078012N Gong Jianlin A0078102N Wu Xianqun

2. Functionality • Get 3NF • Find Closure • Membership Test • Find Keys

3. User Interface

4. Input • To use this tool, user need to enter the function dependencies first.

5. Get 3NF • After entering the function dependencies, click button ‘Get 3NF’ then a schema in 3NF with all the keys will be generated in the output area

6. Find Closure • Click button ‘Find Closure’

7. Membership Test • Click button ‘Membership Test’

8. Find Keys • Click button ‘Find Keys’

9. Algorithm • Generate lossless 3NF schema with all the keys • Find Keys

10. 3NF • Algorithm is based on Bernstein Algorithm • Shortcoming: • Does not guarantee Losslessness. • Does not find all the keys.

11. Lossless • When applying Bernstein Algorithm, attributes may be eliminated. • Solution: After each step which is possible to loss an attribute, the normalizer will check if the attributes eliminated is still in the schema. If not,create a relation for this attribute.

12. Lossless

13. Find all keys • Bernstein Algorithm only give one explicit key. • Solution: After applying Bernstein Algorithm, the normalizer will use the functionality Find Keys to get all the keys of the normalized schema.

14. Find all keys

15. Find Keys • Algorithm published by HosseinSaiedian and Thomas Spencer From Department of Computer science, University of Nebraska in1993

16. Find Keys • Step1: Find L,R,B from R • Step2: Check if L is a key • If yes then it’s the only key • Step3: Find keys in L+B • Keep adding B in turn to L, check if it is a key until all the case reached.

17. Q&A