questions in query on 7.1 and 7.2

On Mon, 29 Jul 2002, Alex Cheung Tin Ka wrote:

Dear All,
I have a table progress which contain "duration" text,
"op_str_time" text, "form_status" integer, "ao_eamil" text and
"ao_res_time" timestamp.

I have run the following query successful in pgsql 7.1 but failed in version 7.2.

select duration, op_str_time from progress where form_status = 4 and
ao_email = 'abc@vtc.edu.hk' and ao_res_time is not null and
extract(month from timestamp(op_str_time)) = 4;

timestamp(n) is now a type specifier. You can either double
quote timestamp (which will make it resolve as the call) or
better yet, use the sql cast syntax.