MYSQL優化 'IN' AND 'ORDER BY'

Question

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

ID SELECT_TYPE表型possible_keys鍵key_len REF行額外 1個SIMPLE test_askcomment所有主NULL NULL NULL 3使用其中;使用文件排序

Answer 1

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

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

嘗試爲您coloumns要在其上使用WHERE子句或選擇coloumns