如何获得去年的第一个 6 个月，即（1-26 周）和最后 6 个月（26-52 周）以及使用 postgresql 从当前日期获得最后 5 个星期

Question

如何获取去年的前 6 个月，即（1-26 周）和最后 6 个月（26-52 周）以及如何使用 postgresql 获取当前日期的最后 5 周。

像下面的table结构

Id Title Description current_week_number current_year
-----------------------------------------------------

123 abc  descr        48                 2021
456 def  descr1       45                 2020

基于我尝试获取数据的周数和年份。

有人可以帮忙吗？

谢谢

Answer 1

--records from 1st half of this year, based on week number
select  Id, Title, Description, current_week_number, current_year
from    your_table
where   current_year=extract('year' from now())::int
and     current_week_number<=26;
--records from 2nd half of this year, based on week number
select  Id, Title, Description, current_week_number, current_year
from    your_table
where   current_year=extract('year' from now())::int
and     current_week_number>26;

关于问题的原始形式，获取实际周数：使用 generate_series(date,date,interval) and extract('field' from date).

with first_26_weeks_of_last_year as 
(   select extract('week' from weeks) weeks
    from generate_series(
            make_date(  extract('year' from 'today'::timestamp-'1 year'::interval)::int,
                        1,
                        1
                    ),
            make_date(  extract('year' from 'today'::timestamp-'1 year'::interval)::int,
                        1,
                        1
                    )+'25 weeks'::interval,
            '1 week'::interval) weeks),
    last_6_months_of_last_year as 
(   select extract('week' from weeks) weeks
    from generate_series(
            make_date(  extract('year' from 'today'::timestamp-'1 year'::interval)::int,
                        12,
                        31
                    ),
            make_date(  extract('year' from 'today'::timestamp-'1 year'::interval)::int,
                        12,
                        31
                    )-'6 months'::interval,
            '1 week'::interval) weeks),
    five_weeks_from_this_week as 
(   select extract('week' from weeks) weeks
    from generate_series(
            'today'::date,
            'today'::date+'4 weeks'::interval,
            '1 week'::interval) weeks)
select 'first_26_weeks_of_last_year',a.weeks
from first_26_weeks_of_last_year a
union all
select 'last_6_months_of_last_year',a.weeks
from last_6_months_of_last_year a
union all
select 'five_weeks_from_this_week',a.weeks
from five_weeks_from_this_week a;

Answer 2

查询最近 6 个月到现在的 table :

SELECT *
  FROM your_table
 WHERE (current_year || '0101') :: date + interval '7 days' * current_week >= Now() - interval '6 months'
   AND (current_year || '0101') :: date + interval '7 days' * current_week <= Now()

查询最近12个月到最近6个月的table:

SELECT *
  FROM your_table
 WHERE (current_year || '0101') :: date + interval '7 days' * current_week <= Now() - interval '6 months'
   AND (current_year || '0101') :: date + interval '7 days' * current_week >= Now() - interval '12 months'

查询当年前6个月的table:

SELECT *
  FROM your_table
 WHERE (current_year || '0101') :: date + interval '7 days' * current_week >= (extract(year from Now()) || '0101') :: date
   AND (current_year || '0101') :: date + interval '7 days' * current_week <= (extract(year from Now()) || '0101') :: date + interval '6 months'

查询当年最后6个月的table:

SELECT *
  FROM your_table
 WHERE (current_year || '0101') :: date + interval '7 days' * current_week >= (extract(year from Now()) || '0101') :: date + interval '6 months'
   AND (current_year || '0101') :: date + interval '7 days' * current_week <= (extract(year from Now()) || '0101') :: date + interval '12 months'

如何获得去年的第一个 6 个月，即（1-26 周）和最后 6 个月（26-52 周）以及使用 postgresql 从当前日期获得最后 5 个星期

How to get the 1st 6months i.e.(1-26weeks) and last 6months (26-52 weeks) from last year & also get last 5weeks from current date using postgresql

postgresql

postgresql-9.3