Re: More on unique vs distinct - Mailing list pgsql-general

On Nov 20, 2006, at 12:27 PM, Wm.A.Stafford wrote:

> I guess I should have been a bit more specific.  Here is an example
> of the type of query I'm finding in the Oracle app and the results
> of my attempt to find  a PostgreSQL equivalent.
>
> select count(unique 'source_id') from obis_sources;
> pgAdmin III query responds:
> ERROR:  syntax error at or near "'source_id'" at character 23
>
> select count(distinct 'source_id') from obis_sources;
> pgAdmin III query responds:
> ERROR:  could not identify an equality operator for type "unknown"

The single quotes are confusing things here, it treats 'source_id' as
a literal string instead of a column name. Try it without the quotes:

   select count(distinct source_id) from obis_sources;

hth,

  -Casey