Re: Concatenating string fields with GROUP BY clause

I was just working on a similar problem. I resulted in to doing it in code.
HAVING would be the avenue, but it is just like a where clause and you can't
say HAVING previous record's g field=this record's g field. :-( You must
sort first by the g field then just spin through while the g fields are the
same.

If anyone knows how to to it within SQL only, I'd appreciate knowing too.

-----Original Message-----
From: pgsql-novice-owner(at)postgresql(dot)org
[mailto:pgsql-novice-owner(at)postgresql(dot)org]On Behalf Of Brian G. Huber
Sent: Tuesday, September 09, 2003 2:03 PM
To: Jeffrey Melloy
Cc: Godshall Michael; pgsql-novice(at)postgresql(dot)org
Subject: Re: [NOVICE] Concatenating string fields with GROUP BY clause

Thanks for the example Jeff - Well said - that is what I'm trying to do.
----- Original Message -----
From: Jeffrey Melloy
To: Brian G. Huber
Cc: Godshall Michael ; pgsql-novice(at)postgresql(dot)org
Sent: Tuesday, September 09, 2003 12:52 PM
Subject: Re: [NOVICE] Concatenating string fields with GROUP BY clause

I think what he's trying to do is this:
a | b | g
1 | sun | 1
2 | shoe | 1
3 | pea | 2
4 | door | 2

he gets this as the response:
group, sum, concat
1, 3, sunshoe
2, 7, peadoor

So a "concatenation aggregate"

That being said, I can't think of any simple way to do it in SQL.

Jeff
On Tuesday, September 9, 2003, at 12:29 PM, Brian G. Huber wrote:

Thanks for the response - but II does not seem to work as an aggregate
function - for example - if I use:

SELECT groupid, sum(numeric_field), ||(text_field) FROM table GROUP BY
groupid

I get

ERROR: Unable to identify a prefix operator '||' for type 'text'
You may need to add parentheses or an explicit cast

Therefore, I think II concatenates two text columns, but does not
aggregate. It would seem this is fairly common but there is no text
aggregation function listed in 6.14 Aggregate Functions!!!
----- Original Message -----

From: Godshall Michael
To: 'Brian G. Huber' ; pgsql-novice(at)postgresql(dot)org
Sent: Tuesday, September 09, 2003 12:10 PM
Subject: Re: [NOVICE] Concatenating string fields with GROUP BY clause

Concatenate is done with || in postgresql

-----Original Message-----
From: Brian G. Huber [mailto:brianghuber(at)yahoo(dot)com]
Sent: Tuesday, September 09, 2003 12:02 PM
To: pgsql-novice(at)postgresql(dot)org
Subject: [NOVICE] Concatenating string fields with GROUP BY clause

Hi -

I am trying to concatenate a text field in a query with a group by
clause, similar to a sum() function on a numeric value - for example:

SELECT groupid, sum(numeric_field), ???(text_field) FROM table GROUP
BY groupid

but I cannot find a function that will concatenate the text fields.
Any comments appreciated!

TIA,BGH