pg_select in a tcl script - Mailing list pgsql-interfaces

Hi

The documentation for pg_select says that "the return result is either
an error message or a handle for a query result".

How can I catch this output? and How do I determine if it is an error or
a handle?

I have tried
   set res [pg_select ...]   pg_result res -status
complains that res is not a result handle, it seems to be a null value.

Thanks in advance for and help or ideas

Steve