Chapter 3 Building Physical Diagrams
Referential integrity is a collection of rules that govern data consistency between primary keys, alternate keys and foreign keys.
Referential integrity dictates what happens when you update or delete a value in a referenced column in the parent table, and when you delete a row containing a referenced column from the parent table.
You can implement referential integrity using one of two methods:
| Referential integrity | Description |
|---|---|
| Declarative | Referential integrity constraints are defined for particular references. When the reference is generated the target DBMS evaluates the reference validity and generates appropriate error messages |
| Using triggers | Referential integrity constraints are implemented by triggers based on the integrity constraints defined in the reference property sheet. The trigger evaluates reference validity and generates appropriate user-defined error messages |
Referential integrity as a generation option
For certain target databases you can define referential integrity as a generation option. However many databases do not accept referential integrity as a generation option (in a trigger or a declaration). In these cases, when you generate a database generation script, it does not include the definition of referential integrity.
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