Re: Concatenating multiple fetches into a single string

Thanks for your reply.

But how to use this comma_aggregate( ) function to concatenate the fetched
columns values from a select statement. In my example my select stmt fetches
the following 3 rows. How can I use this function to concatenate them.

Select full_name FROM project_members where project_members.project_role_id
in ( ' x,y,z ') ;
full_name---------------DavidPostgresplpgsql

Expected return string is - 'David,Postgres,Plsql'

Regards
Kumar
----- Original Message ----- 
From: "Tomasz Myrta" <jasiek@klaster.net>
To: "Kumar" <sgnerd@yahoo.com.sg>
Cc: "psql" <pgsql-sql@postgresql.org>
Sent: Tuesday, December 02, 2003 1:31 AM
Subject: Re: [SQL] Concatenating multiple fetches into a single string


> Dnia 2003-12-01 13:01, Użytkownik Kumar napisał:
> > Dear Friends,
> >
> > I am doing a migration from SQL server to Postgres SQL. A simple select
> > fetches the following names.
> >
> > select full_name FROM project_members where
> > project_members.project_role_id in (' + @p_res_ids + ') ;
> >
> > Let us say if the results are
> >
> > full_name
> > ---------------
> > David
> > Postgres
> > plpgsql
> >
> > I need to send the out put as David,Postgres,Plsql -- one string,
> > concatenates the fetches from multiple rows. This was handled in SQL
> > server with a cursor.
>
> I can't find simpler function (if I remember well, there is such one),
> so there is my version of aggregate function you need:
>
>
> create or replace function comma_aggregate(varchar,varchar) returns
> varchar as '
> begin
>   if length($1)>0 and length($2)>0 then
>       return $1 || '', '' || $2;
>   elsif length($2)>0 then
>     return $2;
>   end if;
>   return $1;
> end;
> ' language 'plpgsql';
>
> drop aggregate comma(varchar) cascade;
> create aggregate comma (basetype=varchar, sfunc=comma_aggregate,
> stype=varchar, initcond='' );
>
> Regards,
> Tomasz Myrta
>
>
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