Обсуждение: distinct

I have attempted to run
select distinct col1 from tablename;
and it runs fine.

When I run it in a real world environment:
select distinct col1, col2, col3, col4 from tablename order by col1 desc, col2;
It returns all the values from col1 which appears to be the same thing as not using distinct at all.

Am I missing something? I'd like only distinct values on col1 and then I'll sort, include, or exclude the other
columns.

Andrew

Andrew Otwell, UNIX/NT SysAdmin
andrew@networkcomputerz.com
http://www.NetworkComputerz.com

On Tue, 3 Oct 2000 andrew@networkcomputerz.com wrote:

> I have attempted to run
> select distinct col1 from tablename;
> and it runs fine.
>
> When I run it in a real world environment: select distinct col1, col2,
> col3, col4 from tablename order by col1 desc, col2; It returns all the
> values from col1 which appears to be the same thing as not using
> distinct at all.

The DISTINCT constraint applies to all of the columns you are selecting,
not just the first one -- it selects all of the distinct TUPLES from the
query.

Brett W. McCoy
                                              http://www.chapelperilous.net
---------------------------------------------------------------------------
The Kennedy Constant:
    Don't get mad -- get even.