PostgreSQL得出兩個timestamp的秒數差值

sql語句

SELECT EXTRACT(EPOCH FROM (TIMESTAMP '2017-12-16 12:21:13'- TIMESTAMP '2017-12-15 12:21:00'));

=>

 86413

計算兩個時間的差值更新另一個時間字段

UPDATE your_table
SET this_time=(EXTRACT(EPOCH FROM (time_a-time_b)));