Hi a probably dumb question on Referential Integrity: I think I understand the basic idea/motivation for it, but one thing I am confused about is this: just when/how do we declare a column in a given table T' to be a foreign key related to the primary key for table T? Is it when we design/create table T' ? I know how, in ACCESS BQE to declare a field to be a primary key, but I have not seen how to make/declare a field in another table to be a foreign key associated to the primary key (though, strangely, once these two keys have been declared, I do know how to enforce referential integrity). And how is this done in SQL? Thanks in Advance.