Convert time to seconds in PostgreSQL - postgresql

Question

I have a time value 04:30:25 that I want to convert to seconds.
Is there any dedicated function to do this?
I know that we can extract hours, minutes and seconds, then calculate the seconds.
SELECT EXTRACT(hour FROM t)*60*60
+ EXTRACT(minutes FROM t)*60
+ EXTRACT(seconds FROM t)
FROM test;
But I want some other way...

Answer 1

Have you tried using:
SELECT EXTRACT(EPOCH FROM INTERVAL '04:30:25');
If that doesn't work you could try to prefix your time value with '1970-01-01' and try:
SELECT EXTRACT(EPOCH FROM TIMESTAMP '1970-01-01 04:30:25');
Not tested but it seems these are your only options. Probably.

Answer 2

You may skip epoch or interval, ie:
SELECT EXTRACT(EPOCH FROM column ) from table

Answer 3

Perhaps you can make it a function (just a quick setup, please review and change as needed)?
CREATE OR REPLACE FUNCTION to_seconds(t text)
RETURNS integer AS
$BODY$
DECLARE
hs INTEGER;
ms INTEGER;
s INTEGER;
BEGIN
SELECT (EXTRACT( HOUR FROM t::time) * 60*60) INTO hs;
SELECT (EXTRACT (MINUTES FROM t::time) * 60) INTO ms;
SELECT (EXTRACT (SECONDS from t::time)) INTO s;
SELECT (hs + ms + s) INTO s;
RETURN s;
END;
$BODY$
LANGUAGE 'plpgsql';
Then just use it in your queries:
SELECT to_seconds('04:30:25');
Returns:
16225

Answer 4

If you want to emulate MySQL's time_to_sec function, you could use a function like this:
CREATE OR REPLACE FUNCTION time_to_sec(t text)
RETURNS integer AS
$BODY$
DECLARE
s INTEGER;
BEGIN
SELECT (EXTRACT (EPOCH FROM t::interval)) INTO s;
RETURN s;
END;
$BODY$
LANGUAGE 'plpgsql';
It has the advantage that it will work with PostgreSQL intervals (ie: more than 24-hour periods), which would break the to_seconds function in the accepted answer.

Answer 5

As a simplified approach to #hdiogenes solution, just use this in the query:
SELECT EXTRACT (EPOCH FROM '04:30:25'::time)

Answer 6

from_seconds also to convert back
CREATE OR REPLACE FUNCTION from_seconds(t integer)
RETURNS time AS
$BODY$
DECLARE
h INTEGER;
m INTEGER;
s INTEGER;
rv TIME;
BEGIN
SELECT t / 3600 INTO h;
SELECT t % 3600 / 60 INTO m;
SELECT t % 60 INTO s;
SELECT (h::text || ':' || m::text || ':' || s::text)::time INTO rv;
RETURN rv;
END;
$BODY$
LANGUAGE 'plpgsql';