postgresql 计算时间差

按日期计算天数差

# select (('2019-11-18 12:05'::timestamp)::date - ('2019-10-18 12:05'::timestamp)::date) as day;
 day 
-----
  31

# select (('2019-11-18 00:05'::timestamp)::date - ('2019-10-18 12:05'::timestamp)::date) as day;
 day 
-----
  31
(1 row)

按时间计算天数差

# select date_part('day', '2019-11-18 12:05'::timestamp - '2019-10-18 12:05'::timestamp);
 date_part 
-----------
        31
(1 row)


# select date_part('day', '2019-11-18 00:05'::timestamp - '2019-10-18 12:05'::timestamp);
 date_part 
-----------
        30
(1 row)

使用age计算时间差

# select extract(day from (age('2019-11-18 12:05'::date , '2019-10-18 12:05'::date))) as day;
 day 
-----
   0
(1 row)

# select age('2019-11-18 12:05'::date , '2019-10-18 12:05'::date);
  age  
-------
 1 mon
(1 row)

 #select age('2019-10-18 12:05'::timestamp, '2011-09-16 12:05'::timestamp);
         age          
----------------------
 8 years 1 mon 2 days
(1 row)

postgresq age

https://www.postgresql.org/docs/12/functions-datetime.html