2. Normalization The process of organizing data in tables in a form that is useable in a data base Tasks involved in Normalization: Removing repetitive information Making sure each record occupies only one row Determining a piece of data that will uniquely identify each row Establish how each table’s data relates to other tables
3. Entity-Relationship Diagram (ERD) Model that shows logical relationships and interaction among system entities The Transaction liking the entities, logs hours on, is a third entity with its own characteristics, this entity is called an associative entity M and N denote the relationship as many to many Many employees may logs hours on different projects Logs hours on Employee Projects M N Time Keeping
4. ERD With Cardinality Notation The marks by the entities represent their cardinality Cardinality the numeric relationship and shows how instances of one entity relate to instances of another In the example one employee, or many employees, or none, can log hours on one project, many projects or no projects Logs hours on Employee Projects Time Keeping
5. Tables for Entities in 3NF Employee Projects Associates records in time keeping with records in Employee Associates records in time keeping with records in Projects Sum total of all hours in records in Time Keeping with corresponding the project # Time Keeping
6. Tasks Indentify all entities Create an initial ERD Assign all data elements to entities Verify all data dictionary entities Create tables in standard notation
7. Tasks Remove repeating groups (1NF) Remove fields from a table if not dependant on Primary key (2NF) Ensure every non-key field depend on the key, the whole key and nothing but the key Identify Keys Identify table relationships
8. Concurrent Tasks Identify all entities Assign all data elements to entities Verify all data dictionary entities