RE: counting distinct rows on more than one column - Mailing list pgsql-sql

From Jeff Eckermann
Subject RE: counting distinct rows on more than one column
Date
Msg-id 08CD1781F85AD4118E0800A0C9B8580B0949E1@NEZU
Whole thread Raw
In response to counting distinct rows on more than one column  (Dirk Lutzebaeck <lutzeb@aeccom.com>)
List pgsql-sql
I don't think this will necessarily work:

field1 | field2
aa     |  ab
a       |  aab

These are two distinct rows, so should be counted as two.
The proposed method would count them as one.
You can get around this problem by doing:
count (distinct (a || x || b))
where x is some character not found in your data.

> -----Original Message-----
> From:    Dirk Lutzebaeck [SMTP:lutzeb@aeccom.com]
> Sent:    Wednesday, March 28, 2001 1:32 PM
> To:    Michael Fork
> Cc:    pgsql-sql@postgresql.org
> Subject:    Re: counting distinct rows on more than one column
> 
> Michael Fork writes:
>  > In 7.0.3, I believe the following would work:
>  > 
>  > SELECT count(distinct(a || b)) FROM t;
> 
> Great, this works! I don't quite get it why...
> 
> Dirk
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 3: if posting/reading through Usenet, please send an appropriate
> subscribe-nomail command to majordomo@postgresql.org so that your
> message can get through to the mailing list cleanly


pgsql-sql by date:

Previous
From: Stephan Szabo
Date:
Subject: Re: DELETE FROM fails with error
Next
From: "Jim Ballard"
Date:
Subject: Re: RE: counting distinct rows on more than one column