PG时间计算
PG数据库，时间计算使用场景总结
日期之差
--**获取秒差**
SELECT round(date_part('epoch', TIMESTAMP '2019-05-05 12:11:20' - TIMESTAMP '2019-05-05 10:10:10'));
--**获取分钟差**
SELECT round(date_part('epoch', TIMESTAMP '2019-05-05 12:11:20' - TIMESTAMP '2019-05-05 10:10:10')/60);
--**获取小时差**
SELECT round(date_part('epoch', TIMESTAMP '2019-05-05 12:11:20' - TIMESTAMP '2019-05-05 10:10:10')/60/60);
--**获取天数差**
SELECT Date('2019-06-05') - Date('2019-05-03');
--**获取月份差**
select extract(year from age(TIMESTAMP '2018-04-05',TIMESTAMP '2017-02-04')) * 12 + extract(MONTH from age(TIMESTAMP '2019-04-05',TIMESTAMP '2017-02-04'));
--**获取年份差**
SELECT extract(year from age(TIMESTAMP '2018-04-05',TIMESTAMP '2017-02-04'));
-- 获取月份
SELECT date_part('month', cast('2023-08-11' as TIMESTAMP) );
--获取星期几1-6，星期天是0
SELECT date_part('dow', cast('2023-08-12' as TIMESTAMP) );
-- 获取年
SELECT date_part('year', cast('2023-08-11' as TIMESTAMP) );
-- 获取日
SELECT date_part('day', cast('2023-08-12' as TIMESTAMP) );