Question

Ok, so I’m trying to query my database with MYSQL that holds a list of meeting dates. The code for each meeting has a predefined pattern:

The first two digits are the year EG ’12’ for 2012′
The next two digits are 01 to 12 to cover the month
The next two digits are 01 to 31 to cover days in the month

I need to apply these rules, because during testing of the database people put in invalid numbers in the meeting code. This is the easiest way to eliminate false meetings when querying the database.

My question is, what would be the most efficient way to apply these rules?

Answer 1

delete from your_table
where substring(code, 3, 2) not between 1 and 12 /* month */
  and substring(code, 5, 2) not between 1 and 31  /* day */
  and code not regexp '^[0-9]{6}$';  /* general check */