问题
So I am building a database for a police station in access. I have a reports super-class that is divided into several sub-classes.From what my books tell me the supper-class should be the one with the "ID" that is the primary key
and that the ID should be passed onto the sub classes so that there are no 2 sub-classes with the same ID .How do I make a validation rule that doesn't allow to make a new sub-clas report if that ID doesn't exists or is being used by other sub classes
回答1:
There is no way insertion in a table can check whether that primary key is present in another table apart from either forcing this constraint through business rule or by using DB Trigger. You need to analyse your DB Model again and try to identify a good design.
来源：https://stackoverflow.com/questions/40588805/is-a-relationship-primary-key-validation-rules