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                合規國際互聯網加速 OSASE為企業客戶提供高速穩定SD-WAN國際加速解決方案。 廣告
                >[success]### 查詢優化神器 - explain命令 具體用法和字段含義可以參考官網[explain-output](http://dev.mysql.com/doc/refman/5.5/en/explain-output.html),這里需要強調rows是核心指標,絕大部分rows小的語句執行一定很快(有例外,下面會講到)。所以優化語句基本上都是在優化rows。 ``` EXPLAIN SELECT `username` FROM user WHERE `id` = 2 ``` ![](https://img.kancloud.cn/85/71/8571a3aca61fbc61671789e26c89e3fd_942x369.png)
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