Re: Converting Rows to Columns

It sounds like you want a crosstab query. There is probably (I don't know
what version of postgres you're using) a contrib package called "tablefunc"
that includes the crosstab functions you're looking for.

_____

From: pgsql-general-owner(at)postgresql(dot)org
[mailto:pgsql-general-owner(at)postgresql(dot)org] On Behalf Of Joshua Berry
Sent: Tuesday, May 05, 2009 9:39 AM
To: pgsql-general(at)postgresql(dot)org
Subject: [GENERAL] Converting Rows to Columns

Greetings all,

I know that this is an elementary question, so I'm just asking for a pointer
in the right direction.

I have a query like this that tries to link Retail shops (from the table
aliased as 'a') to sales reps (from the table aliased as 'e') that service
the given Retail shop:

select a.id_pdv, e.apellido ||', ' || e.nombre as seller_name from tbl_pdvs
a join tbl_circuitos b using (id_circuito) join tbl_frecuencias c on
b.id_circuito = c.id_circuito join tbl_rutas d on c.id_ruta = d.id_ruta join
tbl_vendedores e on d.vendedor = e.id_vendedor order by a.id_pdv limit 4;

id_pdv | seller_name

---------+-------------------

1000001 | COLON, CRISTOBOL

1000001 | LOPEZ, CARLOS

1000002 | COLON, CRISTOBOL

1000002 | LUGO, FERNANDO

As you can see, there are two salesmen that service this shop.

What I need is to be able to create a report that has each unique id_pdv as
a row of the result set, with three columns available to show up to three
salemen that are assigned to the route.

So this would give something like this:

id_pdv | seller_name1 | seller_name2 | seller_name3

---------+------------------+----------------+----------------

1000001 | COLON, CRISTOBOL | LOPEZ, CARLOS | (\N or '')

1000002 | COLON, CRISTOBOL | LUGO, FERNANDO | (\N or '')

Note that the order of the sellers does not matter.

Any tips? I've googled 'sql convert rows to columns' and got some results
that appear to be mssql specific. On Stackoverflow there is an example of
how to convert columns to rows using UNION, but not visa versa.

Thanks in advance!

Joshua

Joshua Berry

Software Engineer

Opentech, S.A.

+(595 21) 282557 Work

+(595) 981 330 701 Mobile