The hours_between() function determines the truncated number of full hours between two timestamps.
int = hours_between(timestamp t1, timestamp t2);
The t1 value specifies the beginning timestamp.
The t2 value specifies the ending timestamp.
select hours_between('1996-02-27 06:12:33' , '1996-03-01 07:12:33');
HOURS_BETWEEN
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73
(1 row)