From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | "A(dot)M(dot)" <agentm(at)themactionfaction(dot)com> |
Cc: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: SELECT table_type FROM table; |
Date: | 2006-05-26 15:26:02 |
Message-ID: | 26160.1148657162@sss.pgh.pa.us |
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Thread: | |
Lists: | pgsql-general |
"A.M." <agentm(at)themactionfaction(dot)com> writes:
> agentm=# select testo from testo;
> testo
> -----------
> (1,hello)
> (2,text)
> (2 rows)
> Obviously, this is intentional behavior but where is it documented?
Well, it's mentioned in passing in section 32.4.2 "SQL Functions on
Composite Types",
http://www.postgresql.org/docs/8.1/static/xfunc-sql.html#AEN31648
where it says "The table row can alternatively be referenced using just
the table name". Personally I prefer the syntax "table.*"; the syntax
without * is a holdover from PostQUEL IIRC.
> agentm=# select *::nice from testo;
> ERROR: syntax error at or near "::" at character 9
The syntactically right thing would be
regression=# select testo::nice from testo;
ERROR: cannot cast type testo to nice
or
regression=# select (testo.*)::nice from testo;
ERROR: cannot cast type testo to nice
We don't have any automatic support for casts from one composite type to
another, but you can add your own:
regression=# create function nice(testo) returns nice language sql as $$
regression$# select $1.* $$ strict immutable;
CREATE FUNCTION
regression=# create cast(testo as nice) with function nice(testo);
CREATE CAST
regression=# select (testo.*)::nice from testo;
testo
-----------
(1,hello)
(2,text)
(2 rows)
regards, tom lane
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