Re: Return Next and Return Query

2009/12/23 Wappler, Robert <rwappler(at)ophardt(dot)com>:
> Hello,
>
> I’m not quite sure, what’s the difference between RETURN NEXT and RETURN
> QUERY.
>
>
>
> From the documentation (Sec. 38.6) RETURN NEXT returns a table and in my
> understanding with each execution a different table.

it is wrong.

>
> RETURN QUERY appends a result set of a query to the function’s result set,
> i.e. the function returns at most one table.
>
>

RETURN QUERY and RETURN NEXT are almost identical.

RETURN NEXT record push one tuple to function's result set, RETURN
QUERY push setof tuples to function's result set. Both RETURNS are not
final, so you can repeat call both.

BEGIN
RETURN QUERY SELECT * FROM tab WHERE a = 1;
RETURN QUERY SELECT * FROM tab WHERE a = 2;
RETURN;
END;

is correct.

Regards
Pavel Stehule
>
> Where is the difference for the caller? That means: how to determine if one
> or several tables have been returned?

RETURN NEXT variable -- it push one tuple on output
RETURN QUERY query -- it push result of query on output

>
> The result of the function is always of type TABLE/SETOF RECORD.
>
>
>
> --
>
> Regards,
>
> Robert...
>
>