# SQL DELETE 语句

DELETE 语句用于删除表中的记录。

## SQL DELETE 语句

DELETE 语句用于删除表中的行。

### SQL DELETE 语法

     DELETE FROM table_name
     WHERE some_column=some_value;

| 请注意 SQL DELETE 语句中的 WHERE 子句！ WHERE 子句规定哪条记录或者哪些记录需要删除。如果您省略了 WHERE 子句，所有的记录都将被删除！

## 演示数据库

在本教程中，我们将使用众所周知的 Northwind 样本数据库。

下面是选自 "Customers" 表的数据：

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 实例

假设我们要从 "Customers" 表中删除客户 "Alfreds Futterkiste"。

我们使用下面的 SQL 语句：

## 实例

     DELETE FROM Customers
     WHERE CustomerName='Alfreds Futterkiste' AND ContactName='Maria Anders';

现在，"Customers" 表如下所示：

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

## 删除所有数据

您可以在不删除表的情况下，删除表中所有的行。这意味着表结构、属性、索引将保持不变：

     DELETE FROM table_name;

     or

     DELETE * FROM table_name;

注释：在删除记录时要格外小心！因为您不能重来！