Posted By: Anonymous
I have a table which contains a datetime column. I wish to return all records of a given day regardless of the time. Or in other words, if my table only contained the following 4 records, then only the 2nd and 3rd would be returned if I limit to 2012-12-25.
2012-12-24 00:00:00 2012-12-25 00:00:00 2012-12-25 06:00:00 2012-12-26 05:00:00
NEVER EVER use a selector like
DATE(datecolumns) = '2012-12-24' – it is a performance killer:
- it will calculate
DATE()for all rows, including those, that don’t match
- it will make it impossible to use an index for the query
It is much faster to use
SELECT * FROM tablename WHERE columname BETWEEN '2012-12-25 00:00:00' AND '2012-12-25 23:59:59'
as this will allow index use without calculation.
As pointed out by Used_By_Already, in the time since the inital answer in 2012, there have emerged versions of MySQL, where using ’23:59:59′ as a day end is no longer safe. An updated version should read
SELECT * FROM tablename WHERE columname >='2012-12-25 00:00:00' AND columname <'2012-12-26 00:00:00'
The gist of the answer, i.e. the avoidance of a selector on a calculated expression, of course still stands.