group_concat函數詳解

標籤：

1.文法如下：

group_concat([DISTINCT] 要串連的欄位 [Order BY ASC/DESC 排序欄位] [Separator ‘分隔字元‘])

2.基本查詢：

select * from aa;  

結果：

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

3. 以id分組，把name欄位的值列印在一行，逗號分隔(預設)

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

結果：

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

4. 以id分組，把name欄位的值列印在一行，分號分隔

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

結果：

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

5. 以id分組，把去冗餘的name欄位的值列印在一行

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

結果：

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

6. 以id分組，把name欄位的值列印在一行，逗號分隔，以name排倒序

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

結果：

+------+---------------------------------------+
| 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函數詳解