Enforcing Referential Integrity with Triggers
Several options are available to enforce RI, but the trigger is still a viable alternative. The trigger provides a great deal of flexibility and allows you to customize your RI solution to fit your needs. Some of the other alternatives do not provide the same degree of customization.
If you are in a database environment in which multiple databases are used with related data, then the trigger can be invaluable for enforcing referential integrity. The trigger has the ability to span databases, and it can ensure that data rows that are inserted into a table in one database are valid based on rows in another database.
In Listing 29.6, you will re-create and populate the customers and orders tables ...