Summary of ER (Contd.)

Several kinds of integrity constraints can be expressed in the ER model: key constraints, participation constraints. Some foreign key constraints (next week) are also implicit in the definition of a relationship set.
- Some constraints (notably, functional dependencies (also next week)) cannot be expressed in the ER model.
- Constraints play an important role in determining the best database design for an enterprise.

Several kinds of integrity constraints can be expressed in the ER model: key constraints, participation constraints. Some foreign key constraints (next week) are also implicit in the definition of a relationship set.