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MySQL 教程

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MySQL DELETE 语句


MySQL DELETE 语句

DELETE 语句用于删除表中的现有记录。

DELETE 语法

DELETE FROM 表名 WHERE 条件;

注意: 删除表中的记录时要小心!注意 DELETE 语句中的 WHERE 子句。 WHERE 子句指定了要删除的记录。如果省略 WHERE 子句,表中的所有记录都将被删除!


演示数据库

以下是 Northwind 示例数据库中“Customers”表的选段

CustomerID CustomerName ContactName Address City PostalCode Country
1

Alfreds Futterkiste Maria Anders Obere Str. 57 Berlin 12209 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constitución 2222 México D.F. 05021 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 05023 Mexico
4

Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Christina Berglund Berguvsvägen 8 Luleå S-958 22 Sweden


SQL DELETE 示例

以下 SQL 语句将从 "Customers" 表中删除客户 "Alfreds Futterkiste"

示例

DELETE FROM Customers WHERE CustomerName='Alfreds Futterkiste';

“Customers”表现在看起来会是这样

CustomerID CustomerName ContactName Address City PostalCode Country
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constitución 2222 México D.F. 05021 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 05023 Mexico
4

Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK
5 Berglunds snabbköp Christina Berglund Berguvsvägen 8 Luleå S-958 22 Sweden

删除所有记录

可以在不删除表的情况下删除表中的所有行。这意味着表的结构、属性和索引将保持不变。

DELETE FROM 表名;

以下 SQL 语句会删除“Customers”表中的所有行,但不会删除该表本身

示例

DELETE FROM Customers;

通过练习来测试自己

练习

删除 "Customers" 表中 Country 值为 "Norway" 的所有记录。

 Customers
 Country = 'Norway';

开始练习


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