问题描述
在Postgres中,给定Y年的第X周,如何获取该周/年的星期一日期?
示例:
monday_of(1,2020) -> '2020-01-30'
monday_of(33,2020) -> '2020-08-10'
monday_of(53,2020) -> '2020-12-28'
monday_of(54,2020) -> '' (year does not have 54 weeks)
解决方法
您可以使用日期算术。假设yr
和wk
是年和周参数:
date_trunc('week',make_date(yr,1,1)) + (wk- 1) * interval '1 week'
但是请注意,这不会检测到超出范围的周数(但是您可以轻松地添加条件逻辑来处理)。
select yr,wk,date_trunc('week',1)) + (wk- 1) * interval '1 week' res
from (values (1,2020),(33,(53,(54,2020)) as t(wk,yr)
yr | wk | res ---: | -: | :--------------------- 2020 | 1 | 2019-12-30 00:00:00+00 2020 | 33 | 2020-08-10 00:00:00+01 2020 | 53 | 2020-12-28 00:00:00+00 2020 | 54 | 2021-01-04 00:00:00+00