MySQL SELECT用法及代码示例

例子

考虑下表有关一些学生的信息：

可以使用此处的代码创建上述示例表。

所有栏目

要返回表 students 中的所有列：

SELECT * FROM students;



+------------+----------+--------+--------------+------+----------+
| student_id | fname    | lname  | day_enrolled | age  | username |
+------------+----------+--------+--------------+------+----------+
|          1 | Sky      | Towner | 2015-12-03   |   17 | stowner1 |
|          2 | Ben      | Davis  | 2016-04-20   |   19 | bdavis2  |
|          3 | Travis   | Apple  | 2018-08-14   |   18 | tapple3  |
|          4 | Arthur   | David  | 2016-04-01   |   16 | adavid4  |
|          5 | Benjamin | Town   | 2014-01-01   |   17 | btown5   |
+------------+----------+--------+--------------+------+----------+

选择检索所有列本质上等同于获取整个表。

具体栏目

仅从表 students 中检索 fname 和 lname 列(按该顺序)：

SELECT fname, lname FROM students;



+----------+--------+
| fname    | lname  |
+----------+--------+
| Sky      | Towner |
| Ben      | Davis  |
| Travis   | Apple  |
| Arthur   | David  |
| Benjamin | Town   |
+----------+--------+

WHERE 子句

SELECT 可以与 WHERE 子句一起使用，以指定行必须满足才能检索的条件。

仅检索年龄超过 17 的学生：

SELECT * FROM students
WHERE age > 17;



+------------+--------+-------+--------------+------+----------+
| student_id | fname  | lname | day_enrolled | age  | username |
+------------+--------+-------+--------------+------+----------+
|          2 | Ben    | Davis | 2016-04-20   |   19 | bdavis2  |
|          3 | Travis | Apple | 2018-08-14   |   18 | tapple3  |
+------------+--------+-------+--------------+------+----------+

'Ben' 和 'Travis' 是表 students 中唯一比 17 年长的学生。