How to display a unixtimestamp from a timestamp record?

Hello!
again i was faced to a problem i was trying to do create view in wich i
had the next fields:

CREATE TABLE "tbacct" (
"user_name" character varying(32),
"nas_identifier" character varying(15),
"nas_port" int4,
"acct_session_id" character varying(15),
"caller_id" character varying(16),
"called_station_id" character varying(16),
"framed_ip_address" character varying(15),
"acct_disconnect_cause" character varying(40),
"acct_session_time" int4,
"acct_timestamp" timestamp,
"realm" character varying(64)
);

and i need view in wich acct_timestamp is a int8

USERNAME
IP-ADDRESS
74
000B2E5B
NULL
6572
IP-ADDRESS
NULL
4
2000-11-13 14:19:45-03
REALM

and i want it to be displayed something like this:

USERNAME
IP-ADDRESS
74
000B2E5B
NULL
6572
IP-ADDRESS
NULL
4
974135985
REALM

i know it is possible using date_part
select date_part( 'epoch' , timestamp '2000-11-13 14:30:40');
gave the right answer . but when i executte

select user_name, date_part( 'epoch' , timestamp 'acct_timestamp') from
tbacct limit 2;

it said ERROR: Bad timestamp external representation 'acct_timestamp'
how should i represent date_part( 'epoch' , timestamp 'acct_timestamp')
to work?

Thanks in Advance

--
Marcelo Bartsch R.
bartschm(at)psi(dot)com
PSINet Chile

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Microsoft C/C++ Compiler Documentation,
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> select user_name, date_part( 'epoch' , timestamp 'acct_timestamp') from
> tbacct limit 2;
>
> it said ERROR: Bad timestamp external representation 'acct_timestamp'
> how should i represent date_part( 'epoch' , timestamp 'acct_timestamp')
> to work?

select user_name, date_part ('epoch', acct_timestamp) from tbacct limit 2;
should work... the single quotes are making a literal string value, so
your query is saying take the epoch of the timestamp represented by the
literal 'acct_timestamp' rather than the value of the field.