Ok I now know that it really seems to do what I expected. But I still wonder what it does if I use two functions f() and g() that return a different number of rows.
I'm guessing a query such as SELECT id, (f(id)).a, (g(id)).b when f returns 3 rows and g returns two row would yield something like this: id | a1 | b1 id | a2 | b2 id | a3 | <NULL> I haven't tried this, so it could be something completely different. In any case I think this should be documented. Jann Am 08.09.10 15:35, schrieb Jann Röder: > Hi, > I have a question which does not seem to be covered in the > documentation: I have a function f(i) that returns a table with three > columns (a, b, c). > > In the documentation > (http://www.postgresql.org/docs/8.4/interactive/xfunc-sql.html#XFUNC-SQL-FUNCTIONS-RETURNING-SET) > it says that (even though deprecated) you can call such functions in a > SELECT clause like so: > > SELECT id, f(id) FROM some_table . > > This will give me a two column table that looks like this: > > id | (a, b, c) > > However since I want a 4 column table like this > id | a | b | c > > , I do this instead: > > SELECT id, (f(id)).a, (f(id)).b, (f(id)).c FROM some_table. > > However I'm not quite sure if this really gives me what I want (i.e. the > same as in the first query only with the tuple elements as separate > columns). > > Of course I'm open to suggestions on how to do this more elegantly and > also how one can do something like this without using the deprecated > feature of calling a set returning function in SELECT. > > Jann > > -- Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-sql
