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MySQL 教程

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MySQL SQL

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MySQL UPDATE 语句


MySQL UPDATE 语句

UPDATE 语句用于修改表中的现有记录。

UPDATE 语法

UPDATE 表名
SET 列1 = 值1, 列2 = 值2, ...
WHERE condition;

注意: 在更新表中的记录时要小心!请注意 UPDATE 语句中的 WHERE 子句。WHERE 子句指定要更新的记录。如果省略 WHERE 子句,表中的所有记录都将被更新!


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

UPDATE 表

以下 SQL 语句使用新的联系人姓名和新的城市更新第一位客户(CustomerID = 1)。

示例

UPDATE Customers
SET ContactName = 'Alfred Schmidt', City = 'Frankfurt'
WHERE CustomerID = 1;

The selection from the "Customers" table will now look like this

CustomerID CustomerName ContactName Address City PostalCode Country
1

Alfreds Futterkiste Alfred Schmidt Obere Str. 57 Frankfurt 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


更新多条记录

WHERE 子句决定更新多少条记录。

以下 SQL 语句将把国家为“Mexico”的所有记录的 PostalCode 更新为 00000:

示例

UPDATE Customers
SET PostalCode = 00000
WHERE Country = 'Mexico';

The selection from the "Customers" table will now look like this

CustomerID CustomerName ContactName Address City PostalCode Country
1

Alfreds Futterkiste Alfred Schmidt Obere Str. 57 Frankfurt 12209 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constitución 2222 México D.F. 00000 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 00000 Mexico
4

Around the Horn Thomas Hardy 120 Hanover Sq. London WA1 1DP UK

更新警告!

更新记录时要小心。如果省略 WHERE 子句,则所有记录都将被更新!

示例

UPDATE Customers
SET PostalCode = 00000;

The selection from the "Customers" table will now look like this

CustomerID CustomerName ContactName Address City PostalCode Country
1

Alfreds Futterkiste Alfred Schmidt Obere Str. 57 Frankfurt 00000 Germany
2 Ana Trujillo Emparedados y helados Ana Trujillo Avda. de la Constitución 2222 México D.F. 00000 Mexico
3 Antonio Moreno Taquería Antonio Moreno Mataderos 2312 México D.F. 00000 Mexico
4

Around the Horn Thomas Hardy 120 Hanover Sq. London 00000 UK

通过练习来测试自己

练习

更新 Customers 表中所有记录的 City 列。

 Customers
 City = 'Oslo';

开始练习


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