1. Databases & Consistency

2. Database Relational databases : dominant information storage/retrieval system

3. Database Data stored in tables – Each row is a record – Columns define attributes

4. Queries Interact with DB's via queries – SELECT : retrieve some data

5. Queries Interact with DB's via queries – UPDATE : modify some data

6. Normalized Data A table of goals scored in soccer matches…

7. Repetitive Data A table of goals scored in soccer matches… Massive duplication of information about one game – Wasteful – Hard to modify

8. Normalized Data Goal : represent each piece of data only once – Break into separate tables

9. Normalized Data Keys : values used to rapidly look up info in other tables

10. Virtual Table Trick Given these two tables determine who scored on Greece:

11. Virtual Table Trick Join : merge two tables based on keys

12. Virtual Table Trick Projection : throw away columns we don't need

13. Virtual Table Trick Select: throw away rows we don't need

14. Virtual Table Trick Select: throw away rows we don't need

15. Virtual Table Trick Projection : throw away columns we don't need