内连接

规则

返回两个表的公共记录

语法

inner join...on 语法

select * from 表1 inner join 表2 on 表1.公共字段=表2.公共字段

where 语法

select * from 表1，表2 where 表1.公共字段=表2.公共字段

MariaDB [sel]> select * from grades inner join resume on grades.name=resume.name;

+-------+---------+------+----+-------+-----------+

| name | chinese | math | id | name | skill |

+-------+---------+------+----+-------+-----------+

| Sunny | 93 | 96 | 1 | Sunny | php |

| Jerry | 97 | 91 | 3 | Jerry | php,mysql |

+-------+---------+------+----+-------+-----------+

# `2 rows in set (0.008 sec)`

MariaDB [sel]> select * from grades,resume where grades.name=resume.name;

+-------+---------+------+----+-------+-----------+

| name | chinese | math | id | name | skill |

+-------+---------+------+----+-------+-----------+

| Sunny | 93 | 96 | 1 | Sunny | php |

| Jerry | 97 | 91 | 3 | Jerry | php,mysql |

+-------+---------+------+----+-------+-----------+

# `2 rows in set (0.001 sec)`

-- 相同的字段只显示一次

mysql> select s.stuno,stuname,stusex,writtenexam,labexam from stuinfo s inner join stumarks m on s.stuno=m.stuno;

+--------+----------+--------+-------------+---------+

| stuno | stuname | stusex | writtenexam | labexam |

+--------+----------+--------+-------------+---------+

| s25303 | 李斯文 | 女 | 80 | 58 |

| s25302 | 李文才 | 男 | 50 | 90 |

| s25304 | 欧阳俊雄 | 男 | 65 | 50 |

| s25301 | 张秋丽 | 男 | 77 | 82 |

| s25318 | 争青小子 | 男 | 56 | 48 |

+--------+----------+--------+-------------+---------+

# `5 rows in set (0.00 sec)`

内连接中inner可以省略

select * from 表1 join 表2 on 表1.公共字段=表2.公共字段

MariaDB [sel]> select * from grades join resume on grades.name=resume.name;

+-------+---------+------+----+-------+-----------+

| name | chinese | math | id | name | skill |

+-------+---------+------+----+-------+-----------+

| Sunny | 93 | 96 | 1 | Sunny | php |

| Jerry | 97 | 91 | 3 | Jerry | php,mysql |

+-------+---------+------+----+-------+-----------+

# `2 rows in set (0.001 sec)`

如何实现三表查询

select * from 表1 inner join 表2 on 表1.公共字段=表2.公共字段 inner join 表3 on 表2.公共字段=表3.公共字段