INSERT with a composite columnt from query

Reg Me Please wrote:

I have two table like these:

create table compo (
t text,
i int
);

create table tab (
x int,
c compo
);

Then I have a function like this:

create or replace function f_compo()
returns setof compo as $body$
...
$body$ language sql stable;

What I'd need to do is to insert the results from f_compo() into
the table TAB along with a value x.

I expected somthing like this to work:

insert into tab
select 42,row( c.* ) from f_compo() c;

But I get
ERROR: cannot cast type record to compo

The whole exercise seems a bit pointless, but you could do it like this:

INSERT INTO tab SELECT 42, CAST (c AS compo) FROM f_compo() c;

Yours,
Laurenz Albe

Reg Me Please wrote:

What I'd need to do is to insert the results from f_compo() into
the table TAB along with a value x.

I expected somthing like this to work:

insert into tab
select 42,row( c.* ) from f_compo() c;

But I get
ERROR: cannot cast type record to compo

You need to add an explicit cast I believe.

INSERT INTO tab (x,c)
SELECT 42, ROW(c.*)::compo FROM f_compo() c;

Why you don't in the case of INSERT ... VALUES isn't immediately clear
to me.

--
Richard Huxton
Archonet Ltd