Creating a new index can improve the query performance of three SQL simultaneously.
Such as the title
CREATE TABLE `score` (`id` int (11) NOT NULL, `studentid` int (11) NOT NULL, `scientitid` int (11) NOT NULL, `score` int (11) NOT NULL, PRIMARY KEY (`id`) ENGINE=InnoDB DEFAULT CHARSET=utf8;-- A new index can improve the query performance of three SQL simultaneously ALTER TABLE `score` ADD INDEX `score` (`score`, `studentid`, `scientitid`) EXPLAIN SELECT * FROM score WHERE score=100;EXPLAIN SELECT * FROM score WHERE studentid=5 AND score=100;EXPLAIN SELECT * FROM score WHERE studentid=5 AND subjectid=2 AND score=100
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