problems with mysql database indexes
see if indexes can be used
key index (parttime)
key index1 (parttime1,partime)
key index2 (parttime2+parttime3)
1.select id from A3 where parttime > "2018-08-03"
2.select id from A3 where partime2 > "2018-08-03" and parttime3 > "2018-09-23"
which index of 1 and 2 can be used?
without guessing, run EXPLAIN , and you can see whether the index is useful or not.
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