Re: composite Unique constraint and null

  • From: Stephane Faroult <sfaroult@xxxxxxxxxxxx>
  • To: jkstill@xxxxxxxxx
  • Date: Tue, 18 Oct 2005 21:40:19 +0200

The interesting thing to know would be what you are supposed to do with
2,345,678 rows storing (1, null). I'd rather have one row with a
counter, if the quantity matters.

SF

On Tue, 2005-10-18 at 12:24 -0700, Jared Still wrote:
> A unique constraint can be used for this.
> 
> Have you tried it?
> 
> --
> Jared Still
> Certifiable Oracle DBA and Part Time Perl Evangelist
> 
> 
> On 10/18/05, Sandeep Dubey <dubey.sandeep@xxxxxxxxx> wrote:
> > Hi,
> >
> > 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.
> >
> > Eg.
> >
> > 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
> >
> --
> http://www.freelists.org/webpage/oracle-l


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