You'd need to effectively have a one-column table, say, "wrenches", that listed only wrenching tools (with a foreign key constraint to "tools"), and you'd reference that rather than the "tools ...

There are so many problems with foreign key constraints that we don't know where to start: Foreign key constraints make life very complicated, because the foreign key definitions must be stored in a ...

The unique, primary key, and foreign key integrity constraints store data values in an index file. If an index file already exists, it is used; otherwise, one is created.

In particular, this simple query shows the constraints for a given table that are foreign key constraints and which primary key constraints they depend on. displayForeignKeyConstraints.sql ...