MySQL中group_concat函数
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‘])
数据如下:
- mysql> select * from aa;
- +
- | id| name |
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- |1 | 10|
- |1 | 20|
- |1 | 20|
- |2 | 20|
- |3 | 200 |
- |3 | 500 |
- +
- 6 rows in set (0.00 sec)
1.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 aa group by id;
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- | id| group_concat(name) |
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- |1 | 10,20,20|
- |2 | 20 |
- |3 | 200,500|
- +
- 3 rows in set (0.00 sec)
2.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;
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- | id| group_concat(name separator ‘;‘) |
- +
- |1 | 10;20;20 |
- |2 | 20|
- |3 | 200;500 |
- +
- 3 rows in set (0.00 sec)
3.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;
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- | id| group_concat(distinct name) |
- +
- |1 | 10,20|
- |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，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)
mysql分组、合并语句
原文：https://www.cnblogs.com/wgyi140724-/p/11437476.html
