SELECT 语句

SELECT 语句用于从数据库中选取数据。

结果被存储在一个结果表中，称为结果集。

语法

SELECT column_name,column_name FROM table_name;

SELECT * FROM table_name;

示例

示例将使用 RUNOOB 样本数据库。该数据库包含一个表， "Websites" 表。

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

SELECT Column 示例

从 "Websites" 表中选取 "name" 和 "country" 列：

SELECT name,country FROM Websites;

输出结果：

mysql> SELECT name,country FROM websites;

+-----------+---------+
| name      | country |
+-----------+---------+
| Google    | USA     |
| 淘宝       | CN      |
| 菜鸟教程   | CN      |
| 微博       | CN      |
| Facebook   | USA     |
+----+-----------------+

SELECT * 示例

从 "Websites" 表中选取所有列：

SELECT * FROM Websites;

输出结果：

mysql> SELECT * FROM Websites;

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