MID() 函數語法
SELECT MID(column_name, start[, length]) FROM table_name;
| 參數 | 說明 |
|---|
| column_name | 必填，來源欄位 |
| start | 必填，起始位置（從 1 開始） |
| length | 選填，擷取字元數；省略則擷取至字串末尾 |
範例資料：Websites 表
+----+--------------+---------------------------+-------+---------+
| id | name | url | alexa | country |
+----+--------------+---------------------------+-------+---------+
| 1 | Google | https://www.google.cm/ | 1 | USA |
| 2 | 淘寶 | https://www.taobao.com/ | 13 | CN |
| 3 | 菜鳥教程 | https://www.runoob.com/ | 4689 | CN |
| 4 | 微博 | https://weibo.com/ | 20 | CN |
| 5 | Facebook | https://www.facebook.com/ | 3 | USA |
| 7 | stackoverflow| https://stackoverflow.com/ | 0 | IND |
+----+--------------+---------------------------+-------+---------+
實作範例：擷取 name 前 4 字元
SELECT MID(name, 1, 4) AS ShortTitle FROM Websites;
