How to optimize date time search in Mysql?

Question

this is my basic date-time structure:

primary  key(datetime)         key
auot_id  date_time             user_id
1        2010-10-01 20:32:34    1
2        2010-10-02 20:32:34    1
3        2010-11-03 20:32:34    2
4        2010-10-04 20:32:34    1
5        2010-11-05 20:32:34    1

And I want to get the result of the day(date_time) at '2010-10' and the user_id = '1'; My SQL is:

SELECT * FROM datetime WHERE user_id = 1 AND DATE_FORMAT(date,'%Y-%m') = '2010-10'

but the EXPLAIN code display:

SIMPLE datetime ALL (NULL) (NULL) (NULL) (NULL) 5 Using where

so ,this line of code doesn't seem to be very effectively。How could I to construct the table to make my search more effective??

Thank you very much!!

Answer 1

Using a function on a column in a WHERE clause prevents efficient usage of an index on that column. Try this instead:

SELECT *
FROM `datetime`
WHERE user_id = 1
AND `date` >= '2010-10-01' AND `date` < '2010-11-01'

Add an index on (user_id, date).

Answer 2

SELECT *
FROM yourTable
WHERE datatime
BETWEEN '2010-10-01' AND '2010-11-01'

efficient and accepts indexing too.