是否有一种灵活的方法来指定日期范围？

Question

I am working with MySQL.

I have some queries that begin like this:

WITH dates (start_date, end_date) AS (
  SELECT '2020-11-01', '2020-11-02'
    UNION ALL SELECT '2020-11-02', '2020-11-03',
    UNION ALL SELECT '2020-11-03', '2020-11-04')
SELECT dates.start_date, dates.end_date, id, COUNT(*)
 FROM dates 
   INNER JOIN ...

I also sometimes need to run the same query, but with each date range being a week (Monday to Sunday), or a calendar month. Moreover, sometimes there are 100 or more of these, which is quite prone to typos in addition to occupying a lot of lines and taking a long time to write.

Is there more elegant and flexible way to achieve this? Ideally I would like to be able to just specify a overall start date, an overall end date and a period (daily, weekly, monthly, yearly etc)

Answer 1

You can use a recursive CTE:

with recursive dates as (
      select date('2020-11-01') as start_date, date('2020-11-02') as end_date
      union all
      select start_date + interval 1 day, end_date + interval 1 day
      from dates
      where start_date < '2020-12-01'
     )
select *
from dates;

Here is a db<>fiddle. Of course, the logic would be a little different for months.

Answer 2

1. Create some date_ranges table which stores: series identifier, range number, range boundaries.
2. Insert needed series into it each time when you need a series which is not present in this table yet.
3. Use this table as source table in your query (maybe with additional condition which narrows the range if needed).
4. Remove series which will be used never in future.