Mysql優化

一、查詢優化 1.優化count查詢 優化前：SELECT COUNT(SEX = '男') FROM employee 空列會計算進去 優化後：SELECT COUNT(SEX='男' OR NULL) FROM employee 空列不會計算進去 2.優化limit查詢 2.1 使用有索引的列或主鍵進行order by 操作  SELECT * FROM employee WHERE DID

>>阅读原文<<