Fw: questions in query on 7.1 and 7.2

I have try it as following

... extract(month from timestamp '"op_str_time"') = 4...

Seems still not work. I am now curious about pgsql's quotion rule. I am not
very clear when to use single and double quotation.

Regards,
Alex

----- Original Message -----
From: "Stephan Szabo" <sszabo(at)megazone23(dot)bigpanda(dot)com>
To: "Alex Cheung Tin Ka" <tkcheung(at)vtc(dot)edu(dot)hk>
Cc: <pgsql-general(at)postgresql(dot)org>
Sent: Monday, July 29, 2002 10:13 AM
Subject: Re: [GENERAL] 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(at)vtc(dot)edu(dot)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.
>
>
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