how to calculate the time between two timestamps (PostgreSQL)

Question

Calculate the time between these two timestamps in PostgreSQL,
create_time='2017-11-02 05:51:13' and update_time='2017-11-02 07:36:18'
and display it on HH:MM:SS Format. it should display like this 01:45:04

Answer 1

You can try just subtracting the two timestamps, then using to_char to extract out the time portion:

select
    SELECT to_char('2017-11-02 07:36:18'::timestamp -
                   '2017-11-02 05:51:10'::timestamp, 'HH:MI:SS');

Output:

to_char
01:45:08

Demo