key constraint
From: Jian Xu <Jian.Xu_at_mcs.vuw.ac.nz>
Date: Sat, 14 Apr 2001 17:43:37 +1200
Message-ID: <987227398.2119731143_at_news.mcs.vuw.ac.nz>
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.
Date: Sat, 14 Apr 2001 17:43:37 +1200
Message-ID: <987227398.2119731143_at_news.mcs.vuw.ac.nz>
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.
tks and rgs,
jxu
Received on Sat Apr 14 2001 - 07:43:37 CEST