Vanilla MySQL doesn't support any sort of referential integrity. You can use "InnoDB" tables (here) that add that functionality. If you're in a shared hosting ...

Cascading referential integrity constraints are foreign key constraints that tell SQL Server to perform certain actions when a primary key field in a primary key-foreign key relationship is updated or ...

There are two categories of integrity constraints: General constraints, which allow you to restrict the data values that are accepted for the variables in a single data file, such as requiring that ...