PostgreSQL calculate timestampdiff code example
Example 1: postgresql get difference between two dates
select age('2010-04-01', '2012-03-05'),
date_part('year',age('2010-04-01', '2012-03-05')),
date_part('month',age('2010-04-01', '2012-03-05')),
date_part('day',age('2010-04-01', '2012-03-05'));
Example 2: DATEDIFF minute postgres
SELECT (DATE_PART('day', '2011-12-30 08:56:10'::timestamp - '2011-12-30 08:54:55'::timestamp) * 24 * 60 +
DATE_PART('hour', '2011-12-30 08:56:10'::timestamp - '2011-12-30 08:54:55'::timestamp)) * 60 +
DATE_PART('minute', '2011-12-30 08:56:10'::timestamp - '2011-12-30 08:54:55'::timestamp);
SELECT DATE_PART('hour', '08:56:10'::time - '08:54:55'::time) * 60 +
DATE_PART('minute', '08:56:10'::time - '08:54:55'::time);
Example 3: postgres time difference in minutes
CREATE OR REPLACE FUNCTION DateDiff (units VARCHAR(30), start_t TIME, end_t TIME)
RETURNS INT AS $$
DECLARE
diff_interval INTERVAL;
diff INT = 0;
BEGIN
diff_interval = end_t - start_t;
diff = DATE_PART('hour', diff_interval);
IF units IN ('hh', 'hour') THEN
RETURN diff;
END IF;
diff = diff * 60 + DATE_PART('minute', diff_interval);
IF units IN ('mi', 'n', 'minute') THEN
RETURN diff;
END IF;
diff = diff * 60 + DATE_PART('second', diff_interval);
RETURN diff;
END;
$$ LANGUAGE plpgsql;