mysql 获取唯一值_MySQL查询获取唯一值的计数？

要计算列上的唯一值，您需要使用关键字DISTINCT。要了解它是如何完成的，让我们创建一个表。创建表的查询如下-mysql> create table UniqueCountByIPAddress

-> (

-> Id int NOT NULL AUTO_INCREMENT,

-> UserHits int,

-> UserIPAddress varchar(50),

-> PRIMARY KEY(Id)

-> );

使用insert命令在表中插入一些记录。查询如下-mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(10,'127.0.0.1');

mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(10,'127.0.0.1');

mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(20,'127.0.0.1');

mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(20,'127.0.0.2');

mysql> insert into UniqueCountByIPAddress(UserHits,UserIPAddress) values(30,'127.0.0.2');

使用select语句显示表中的所有记录。查询如下-mysql> select *from UniqueCountByIPAddress;

以下是输出-+----+----------+--------------+

| Id | UserHits | UserIPAddress|

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

| 1 | 10 | 127.0.0.1 |

| 2 | 10 | 127.0.0.1 |

| 3 | 20 | 127.0.0.1 |

| 4 | 20 | 127.0.0.1 |

| 5 | 20 | 127.0.0.2 |

| 6 | 20 | 127.0.0.2 |

| 7 | 30 | 127.0.0.2 |

| 8 | 30 | 127.0.0.2 |

| 9 | 30 | 127.0.0.2 |

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

以下是查询以计算'UserIPAddress'列上的不同值-mysql> select UserHits,count(distinct UserIPAddress) as TotalHits

-> from UniqueCountByIPAddress group by UserHits;

以下是输出-+----------+-----------+

| UserHits | TotalHits |

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

| 10 | 1 |

| 20 | 2 |

| 30 | 1 |

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

3 rows in set (0.05 sec)