comparing dates by month and year in mysql

Question

I have a table containing data about events and festivals with following columns recording their start and end dates.

• Start_Date
• End_Date

d

Answer 1

I don't like either of the other two answers, because they do not let the optimizer use an index on start_date. For that, the functions need to be on the current date side.

So, I would go for:

where start_date >= date_add(curdate(), interval 1 - day(curdate()) day) and
      start_date < date_add(date_add(curdate(), interval 1 - day(curdate()) day), interval 1 month)

All the date functions are on curdate(), which does not affect the ability of MySQL to use an index in this case.

You can also include the condition on end_date:

where (start_date >= date_add(curdate(), interval 1 - day(curdate()) day) and
       start_date < date_add(date_add(curdate(), interval 1 - day(curdate()) day), interval 1 month)
      ) and
      end_date <= date_add(curdate(), interval 30 day)

This can still take advantage of an index.

Answer 2

select * from your_table
where year(Start_Date) = year(curdate())
and month(Start_Date) = month(curdate())
and end_date <= curdate() + interval 30 day

Answer 3

DateTime functions are your friends:

SELECT
    *
FROM
    `event`
WHERE
    (MONTH(NOW()) = MONTH(`Start_Date`))
    AND
    (`End_Date` <= (NOW() + INTERVAL 30 DAY))
    AND
    (YEAR(NOW()) = YEAR(`Start_Date`))

Answer 4

Comparing the year and month separately feels messy. I like to contain it in one line. I doubt it will make a noticeable difference in performance, so its purely personal preference.

select * from your_table
where LAST_DAY(Start_Date) = LAST_DAY(curdate())
and end_date <= curdate() + interval 30 day

So all I'm doing is using the last_day function to check the last day of the month of each date and then comparing this common denominator. You could also use

where DATE_FORMAT(Start_Date ,'%Y-%m-01') = DATE_FORMAT(curdate(),'%Y-%m-01')