SELECT COUNT (*) AS num FROM test WHERE ( a = 111AND cid = 21432 OR s_status < > "yes" OR t_status < > yes") AND test . delete_time IS NULL LIMIT 1
explain the statement type is displayed as ALL. How to optimize it?
SELECT COUNT (*) AS num FROM test WHERE ( a = 111AND cid = 21432 OR s_status < > "yes" OR t_status < > yes") AND test . delete_time IS NULL LIMIT 1
explain the statement type is displayed as ALL. How to optimize it?
personal understanding, I hope it will be helpful to you
upstairs correct solution, first of all, to minimize some of the operations said upstairs. Otherwise, it will always be all. :). Look at your sql statement, you can know your requirements, should be the number of statistics. The conditions are a = 111and cid = 21432 | s_status! = yes | t_status! = yes, test.delete is null. The end result is: well, it's impossible, it can't be optimized, (at least I am). First of all, if you want to use an index, disable null and replace it with 0 or something else. Second, yes this do not use different, use like for retrieval, you can cooperate with the if method.
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