MYSQL optimize 'IN' AND 'ORDER BY'

2018-06-08 06:32:16

EXPLAIN 
    SELECT * FROM test_askcomment WHERE cid IN(1,2,3) ORDER BY dateline DESC;

id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE test_askcomment ALL PRIMARY NULL NULL NULL 3 Using where; Using filesort

ALTER TABLE `test_askcomment ` ADD INDEX `index1` (`cid`);

ALTER TABLE `test_askcomment ` ADD INDEX `index2` (`dateline `);

尝试为您使用where子句或选择coloumns的coloumns编制索引

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