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MySQL之SQL函数-1 MySQL中group_concat函数

2014-04-08 14:37 127 查看
本文通过实例介绍了MySQL中的group_concat函数的使用方法。

完整的语法如下:

group_concat([DISTINCT] 要连接的字段 [Order BY ASC/DESC 排序字段] [Separator '分隔符'])

(1)基本查询: 

mysql> select * from table;

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

| id| name |

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

|1 | 10|

|1 | 20|

|1 | 20|

|2 | 20|

|3 | 200  |

|3 | 500  |

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

6 rows in set (0.00 sec)

(2)以id分组,把name字段的值打印在一行,逗号分隔(默认): 

mysql> select id,group_concat(name) from table group by id;

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

| id| group_concat(name) |

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

|1 | 10,20,20|

|2 | 20 |

|3 | 200,500|

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

3 rows in set (0.00 sec)

(3)以id分组,把name字段的值打印在一行,分号分隔:

mysql> select id,group_concat(name separator ';') from aa group by id;

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

| id| group_concat(name separator ';') |

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

|1 | 10;20;20 |

|2 | 20|

|3 | 200;500  |

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

3 rows in set (0.00 sec)

(4)以id分组,把去冗余的name字段的值打印在一行, 逗号分隔:

mysql> select id,group_concat(distinct name) from aa group by id;

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

| id| group_concat(distinct name) |

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

|1 | 10,20|

|2 | 20  |

|3 | 200,500 |

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

3 rows in set (0.00 sec)

(5)以id分组,把name字段的值打印在一行,逗号分隔,以name排倒序: 

mysql> select id,group_concat(name order by name desc) from aa group by id;

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

| id| group_concat(name order by name desc) |

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

|1 | 20,20,10  |

|2 | 20|

|3 | 500,200|

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

3 rows in set (0.00 sec)
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