You need to use the FOR-IN-EXECUTE style of query. That way you can use any string you want (including text passed in as a parameter) to build the query inside the function ...
that is what i want to avoid. (i wrote that in my first mail)
My question was about why it is not possible to do it like this:
....ORDER BY $1
I don't know if it is standards-conform or if someone considers it a usefull feature, but i think it would help users to write capsulated statistics-functions or simply browsable and orderable lists.
You want to build a dynamic query (sorted in different ways depending on a function parameter).
You don't want to use the dynamic query statement (EXECUTE).
The whole point of plpgsql is that the queries can be compiled and pre-planned. If you want to change the sorting then that implies a different plan, which implies using the dynamic query feature.
What you want to do is possible if you use one of the interpreted languages, e.g. pltcl/plperl (plphp?). Of course, that means none of your query plans get compiled.
-- Richard Huxton Archonet Ltd
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