1. Databases & Consistency

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

3. Database
Data stored in tables
Each row is a record

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

5. Normalized Data
Keys : attribute that uniquely identifies record

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

7. Queries
Interact with DB's via queries
WHERE : Limits scope

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

9. Repetitive Data
Duplication of data
Wasteful
Hard to modify

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

11. Normalized Data Use key to look up related records
CustomerID in Orders says which Customer made order

12. Task
Given these two table, print customer name and sale amount for orders on 5/7/2004

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

14. Join Samples
Using a Join between Movies and Boxoffice