#TIL : Index is useless when use function on indexed field

Dec 1, 2015 4 mins read 8d4302659

Index is useless when use function on indexed field

Reality, if using function on indexed field, you will broke indexing by accident. Eg:

WHERE MONTH(`date`) = 11 AND YEAR(`date`) = 2015

Solution is transform the query to comparison query, like this :

WHERE `date` >= '2015-11-01' AND `date` < '2015-12-01'
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