Re: Getting one row for each subquery row...?

Dnia 2003-06-20 07:12, Użytkownik Együd Csaba napisał:

> Hi All,
>  here are my three tables. I wold like to list them in the following way: I
>  need all the columns from t_stockchanges, and one field for the
> productgroup
>  the t_stockchanges.productid belongs to.
> 
>  But one product can belong to many groups, so i would need one row for each
>  group for each product.
> 
>  My bad query is:
>  ------------------------
>  DB=# select t_stockchanges.productid, (select name from t_productgroups
>  where id=(select productgroupid from t_prod_in_pgr where
>  productid=t_stockchanges.productid)) as pgroup from t_stockchanges;
>  ERROR:  More than one tuple returned by a subselect used as an expression.
>  DB=#
>  ---------------
>  Yes, this is absolutelly true, but I would like postgres to give me all the
>  tuples found. How can I ask him to do so?
> 
>  Thank you,
>  -- Csaba
Sorry, if you want all combination of grups and products, you need to rewrite 
your query:

select t_stockchanges.productid, t_productgroups.name as pgroup
from t_stockchanges join t_prod_in using (productid) join t_productgroups on (id=productgroupid)

or something like this.

Tomasz