Ethnographic Approach III

What are the relations (tables) necessary to support the identified tasks?
“Goodness” of relational schemas
- Logical level (related to user interpretation and query formulation).
- Manipulation (storage) level.
Guidelines
- Schema should be easy to explain.
- Avoid Insertion/Deletion/Update anomalies (e.g. if insurance plan details stored in patient demographics relational schema).
- Avoid schemas that can be joined with primary or foreign keys to generate spurious (false) tuples (e.g. schema using patient last_name as key).
ERD—CASE Tools