i'm doing a database project, and met one question about the key constraints. what the question asked is simply " Drop key constraint from the table Cust_Order relation." i just dropped the primary key constraint for that relation, but i'm confused with the "not null" constraint. do i need to drop that constraint also? does any one familiar with the key constraint definition to help me ? the relation definition below:
Table name : Cust_Order
primary key : OrderID OrderID integer 4 n
OrderDate Date y
CustomerID int 4 n
here 'y' means can be null, n means can be not null. the first column is attribute name and the second is data type accordingly.
Not neccesarily. The question is why you are dropping the key constraint. Is it for efficiency reasons or did you make a conceptual mistake in your data model? In the first case the not-null should definitely stay, in the second case you simply have to rethink if they may be null or not.