composite Unique constraint and null

  • From: Sandeep Dubey <dubey.sandeep@xxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Tue, 18 Oct 2005 13:05:47 -0400


I want to enforce a business rule on two columns such that col1, col2
should be unique. However for a given value of col1 nulls should be
allowed in col2. I can not implement that using a simple composite
unique constraint.


create table foo(id number, name varchar2(10));

insert into foo values(1,1);
insert into foo values(1,1); -- should not be allowed

But following should be allowed

insert into foo values(1,null);
insert into foo values(1,null); -- should be allowed

Any ideas!!



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