Re: DISTINCT with NULLs and INT fields

George Pavlov wrote:

> test=# insert into foo values (4::int,4::int);
> INSERT 0 1
> test=# insert into foo values (4::text,4::text);
> ERROR: column "b" is of type integer but expression is of type text
> HINT: You will need to rewrite or cast the expression.
> test=# insert into foo values (cast(4 as int),cast(4 as int));
> INSERT 0 1
> test=# insert into foo values (cast(4 as text),cast(4 as text));
> ERROR: column "b" is of type integer but expression is of type text
> HINT: You will need to rewrite or cast the expression.

The last sentence (and the second one as well -- they are exactly
equivalent) exemplifies that there isn't an implicit typecase from text
to integer. If you use single quotes instead of an explicit cast, the
literal is assumed to be of type "unknown", which _can_ be casted
automatically to integer.

--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support