SQL 学习之UPDATE 语句

解释：
UPDATE 语句用于更新表中的记录。
语法

UPDATE table_name
SET column1=value1,column2=value2,...
WHERE some_column=some_value;

演示库

+----+--------------+---------------------------+-------+---------+
| id | name         | url                       | alexa | country |
+----+--------------+---------------------------+-------+---------+
| 1  | Google       | https://www.google.cm/    | 1     | USA     |
| 2  | 淘宝          | https://www.taobao/   | 13    | CN      |
| 3  | 菜鸟教程      | http://www.runoob/    | 4689  | CN      |
| 4  | 微博          | http://weibo/         | 20    | CN      |
| 5  | Facebook     | https://www.facebook/ | 3     | USA     |
+----+--------------+---------------------------+-------+---------+

UPDATE 实例

UPDATE Websites 
SET alexa='5000', country='USA' 
WHERE name='菜鸟教程';

更新一列数据

UPDATE Websites 
SET alexa='5000', 

+----+--------------+---------------------------+-------+---------+
| id | name         | url                       | alexa | country |
+----+--------------+---------------------------+-------+---------+
| 1  | Google       | https://www.google.cm/    | 5000    | USA     |
| 2  | 淘宝          | https://www.taobao/   | 5000    | CN      |
| 3  | 菜鸟教程      | http://www.runoob/    | 5000   | CN      |
| 4  | 微博          | http://weibo/         | 5000     | CN      |
| 5  | Facebook     | https://www.facebook/ | 5000      | USA     |
+----+--------------+---------------------------+-------+---------+