看看MySQL更新資料、刪除數據-mysql教程-PHP中文網

看看MySQL更新資料、刪除數據

(1)更新資料
(2)刪除資料

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(1)、更新資料

MySQL中使用update語句更新表中的記錄，可以更新特定的行或同事更新所有的行，基本語法如下：

update table_nameset column_name1 = value1,column_name2 = value2,.....,column_namen = valuenwhere (condition);

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【例1】在person表中，更新id值為11的記錄，將age字段值改為15，將name字段值改為LimMing，SQL語句如下;

mysql> update person -> set age =15,name ='LiMing' -> where id =11;Query OK, 1 row affected (0.05 sec)Rows matched: 1 Changed: 1 Warnings: 0mysql> select * from person where id =11;+----+--------+------+---------+| id | name | age | info |+----+--------+------+---------+| 11 | LiMing | 15 | student |+----+--------+------+---------+1 row in set (0.00 sec)

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【範例2】在person表中，更新age值為19-22的記錄，將info欄位值都改為student，SQL語句如下：

mysql> select * from person where age between 19 and 22;+----+---------+------+------------+| id | name | age | info |+----+---------+------+------------+| 1 | Green | 21 | Lawyer || 2 | Suse | 22 | dancer || 4 | Willam | 20 | sports man || 7 | Dale | 22 | cook || 9 | Harry | 21 | magician || 10 | Harriet | 19 | pianist |+----+---------+------+------------+6 rows in set (0.00 sec)mysql> update person set info='student' where age between 19 and 22;Query OK, 0 rows affected (0.00 sec)Rows matched: 0 Changed: 0 Warnings: 0mysql> select * from person where age between 19 and 22;+----+---------+------+---------+| id | name | age | info |+----+---------+------+---------+| 1 | Green | 21 | student || 2 | Suse | 22 | student || 4 | Willam | 20 | student || 7 | Dale | 22 | student || 9 | Harry | 21 | student || 10 | Harriet | 19 | student |+----+---------+------+---------+6 rows in set (0.00 sec)

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#(2)、刪除資料

從資料表刪除資料使用delete語句，允許使用where子句指定刪除條件。 delete語句的基本語法格式如下;

delete from table_name [where < condition>]

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"where"為可選參數，指定刪除條件，如果沒有，delete語句將刪除表中的所有記錄。

【範例1】在person表中，刪除id等於11的記錄。

mysql> select * -> from person -> where id =11;+----+--------+------+---------+| id | name | age | info |+----+--------+------+---------+| 11 | LiMing | 15 | student |+----+--------+------+---------+1 row in set (0.00 sec)mysql> delete from person -> where id = 11;Query OK, 1 row affected (0.05 sec)mysql> select * -> from person -> where id = 11;Empty set (0.00 sec)

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【例2】在person表中，使用delete語句同時刪除多個記錄，在前面update語句中將age字段值為19-22的記錄的info字段值修改為student，在這裡刪除這些記錄，SQL語句如下：

mysql> select * from person where age between 19 and 22;+----+---------+------+---------+| id | name | age | info |+----+---------+------+---------+| 1 | Green | 21 | student || 2 | Suse | 22 | student || 4 | Willam | 20 | student || 7 | Dale | 22 | student || 9 | Harry | 21 | student || 10 | Harriet | 19 | student |+----+---------+------+---------+6 rows in set (0.00 sec)mysql> delete from person where age between 19 and 22;Query OK, 6 rows affected (0.05 sec)mysql> select * from person where age between 19 and 22;Empty set (0.00 sec)

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【例3】刪除person表中所有記錄，SQL語句如下：

mysql> select * from person;+----+---------+------+-----------+| id | name | age | info |+----+---------+------+-----------+| 3 | Mary | 24 | Musician || 5 | Laura | 25 | NULL || 6 | Evans | 27 | secretary || 8 | Edison | 28 | singer || 12 | Beckham | 31 | police |+----+---------+------+-----------+5 rows in set (0.00 sec)mysql> delete from person;Query OK, 5 rows affected (0.05 sec)mysql> select * from person;Empty set (0.00 sec)

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