如何编写 where 子句以动态获取上个月某个日期和当前月份某个日期之间的日期？

Question

I need to write a query where I need all the records between the 26th of last month and the 25th of the current month and if the current date is between 26 and 31 then I need records between 26 and 31 of just this month.

The monthly cycle is from 26 to 25 and the query is supposed to be executed every day. I'm not able to figure out how to write a where clause for this.

this is the structure of the table that I have:

order_id    order_date    bill
  1          2021-02-25    500
  2          2021-02-25    1000
  3          2021-02-26    1500
  4          2021-02-27    150
  5          2021-02-28    25
  6          2021-03-02    78
              .
              .
              .
 4250        2021-03-25    500

Answer 1

The general format of the query might look like this:

select *
from t
where
day(curdate()) between 26 and 31) and order_date between a and b or
day(curdate()) not between 26 and 31) and order_date between c and d

or:

select *
from t
where
order_date between if(curdate()) between 26 and 31, a, c) and if(curdate() between 26 and 31, b, d)

where a, b and c would use date calculations. For a it would be adddate(subdate(curdate(), interval day(curdate()) day), interval 26 day) . b would be last_day(curdate()) .

Answer 2

If you want to write a WHERE clause using the BETWEEN predicate, there is a way to use EXISTS (subquery) .

SELECT * FROM mytable m
WHERE EXISTS
(SELECT 1 FROM (SELECT LAST_DAY(CURDATE() - INTERVAL 25 DAY) d) t
 WHERE m.order_date
    BETWEEN
        d + INTERVAL (-DAY(d)+1+25) DAY
        AND
        d + INTERVAL 25 DAY)

The extraction range is the period obtained by adding 25 to the 1st day and the last day of the month including the start date.

LAST_DAY(CURDATE() - INTERVAL 25 DAY) always maps to the last day of the same month.

2021-02-26 -> 2021-02-01 -> 2021-02-28
2021-02-27 -> 2021-02-02 -> 2021-02-28
2021-02-28 -> 2021-02-03 -> 2021-02-28
2021-03-01 -> 2021-02-04 -> 2021-02-28
:
2021-03-25 -> 2021-02-28 -> 2021-02-28

About d + INTERVAL (-DAY(d)+1+25) DAY , -DAY(d)+1 is the first day, so -DAY(d)+1+25 is 26th of that month. d + INTERVAL 25 DAY is 25th of that next month.

Fiddle