Inference Axioms

1. M Taimoor Khan taimoorkhan@ciit-attock.edu.pk Inference Axioms

2. Course Objectives • Basic Concepts • Tools • Database architecture and design • Flow of data (DFDs) • Mappings (ERDs) • Formulating queries (Relational algebra) • Implementing Schema • Built-in Functions • Extracting data • Working with Joins • Normalization • Improving performance • Advanced topics

3. Normalization • Why Normalization • Functional Dependency • Armstrong’s Axioms • First Normal Form (1NF) • Second Normal Form (2NF) • Third Normal Form (3NF) • Boyce - Codd Normal Form (BCNF)

4. Inference Rules • Called inference axioms or armstrong axioms • These are rules that establish certain FDs from a given set of FDs • These rules are sound

5. Reflexivity • If B is a subset of A then A B, it also implies that A A always hold, that is stName, stAdr stName Or stName stName

6. Augmentation • If we have A B then AC BC that is if stId stName then stId, stAdr stName, stAdr

7. Transitivity • If A B and B C then A C that is If stId prName and prName credits Then stId credits

8. Additivity or Union • If A B and A C then A BC if empId eName and empId qual Then we can write it as empId eName, qual

9. Projectivity or Decomposition • If A BC then A B and A C if empId eName, qual Then we can write it as empId eName and empId qual

10. Pseudotransitivity • If A B and CB D then AC D if stId stName and stName, fName stAdr Then we can write it as stId, fName stAdr

11. Normalization • Why Normalization • Functional Dependency • Armstrong’s Axioms • First Normal Form (1NF) • Second Normal Form (2NF) • Third Normal Form (3NF) • Boyce - Codd Normal Form (BCNF)

12. Lab Activity-12 • Sort a Query • Sort multiple columns in a query • Query with two or more tables • Save a query • Create a parameter query

13. Next Lecture • Normalization