group_concat函数详解

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1.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‘])

2.基本查询：

select * from aa;  

结果：

+------+------+
| id| name |
+------+------+
|1 | 10|
|1 | 20|
|1 | 20|
|2 | 20|
|3 | 200 |
|3 | 500 |
+------+------+
6 rows in set (0.00 sec)

3. 以id分组，把name字段的值打印在一行，逗号分隔(默认)

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

结果：

+------+--------------------+
| id| group_concat(name) |
+------+--------------------+
|1 | 10,20,20|
|2 | 20 |
|3 | 200,500|
+------+--------------------+
3 rows in set (0.00 sec)

4. 以id分组，把name字段的值打印在一行，分号分隔

select id,group_concat(name separator ‘;‘) from aa group by id;  

结果：

+------+----------------------------------+
| id| group_concat(name separator ‘;‘) |
+------+----------------------------------+
|1 | 10;20;20 |
|2 | 20|
|3 | 200;500 |
+------+----------------------------------+
3 rows in set (0.00 sec)

5. 以id分组，把去冗余的name字段的值打印在一行

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

结果：

+------+-----------------------------+
| id| group_concat(distinct name) |
+------+-----------------------------+
|1 | 10,20|
|2 | 20 |
|3 | 200,500 |
+------+-----------------------------+
3 rows in set (0.00 sec)

6. 以id分组，把name字段的值打印在一行，逗号分隔，以name排倒序

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

结果：

+------+---------------------------------------+
| id| group_concat(name order by name desc) |
+------+---------------------------------------+
|1 | 20,20,10 |
|2 | 20|
|3 | 500,200|
+------+---------------------------------------+
3 rows in set (0.00 sec)

group_concat函数详解

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原文地址：http://www.cnblogs.com/longzhongren/p/4775293.html