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

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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.