Re: possible bug with group by?

On Wed, May 24, 2000 at 06:30:49PM -0400, Joseph Shraibman wrote:
> Is this a bug or am I just misunderstanding something?
> 

Not a bug, pgsql is just less willing to cast things willy-nilly
in 7.0 than it was in 6.x.  In this case, the system doesn't know what
'not set' and 'set' are supposed to be, so if can't decide what operator
to use to compare them for grouping. Try something like:
select a, b, case when c is null then 'not set'::text else 'set'::text end  as z from tablea group by a, b, z;

Or even SQL92 compliant:

select a, b, case when c is null then CAST ('not set' AS TEXT)  else CAST
('set' as text) end as z from tablea group by a, b, z;


> 
> playpen=> select a, b, case when c is null then 'not set' else 'set' end
> as z from tablea group by a, b, z;
> ERROR:  Unable to identify an operator '<' for types 'unknown' and
> 'unknown'
>         You will have to retype this query using an explicit cast
> playpen=>
> 

Ross
-- 
Ross J. Reedstrom, Ph.D., <reedstrm@rice.edu> 
NSBRI Research Scientist/Programmer
Computer and Information Technology Institute
Rice University, 6100 S. Main St.,  Houston, TX 77005