Обсуждение: how do i query the type of an object?

Mark Rostron <mrostron@ql2.com> writes:
> Is there some way to query the data-type of '<some value expression>'?

There's a SQL-standard construct called IS OF, and a function called
pg_typeof, but it's not real clear whether either of those would help
you.

            regards, tom lane

Tom Lane wrote:
> Mark Rostron <mrostron@ql2.com> writes:
>
>> Is there some way to query the data-type of '<some value expression>'?
>>
>
> There's a SQL-standard construct called IS OF, and a function called
> pg_typeof, but it's not real clear whether either of those would help
> you.
>
I failed finding IS OF in the pg documentation, however,
http://farrago.sourceforge.net/design/UserDefinedTypesAndRoutines.html
had a reference to it.

postgres=# create table a(a) as select 1;
SELECT 1
postgres=# select * from a where a IS OF (integer);
 a
---
 1
(1 row)

While learning this somehow triggers the 'cool I just learned some new
obscure SQL trick' feeling, I am not sure if it is really useful without
CREATE TYPE foo UNDER bar.

regards,
Yeb Havinga