concat和concat_ws()区别及MySQL的几个实用字符串函数(2)

|    1 | 20   |
|    2 | 20   |
|    3 | 200  |
|    3 | 500  |
+------+------+
6 rows in set (0.00 sec)
3.1 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;
+------+--------------------+
| id   | group_concat(name) |
+------+--------------------+
|    1 | 10,20,20           |
|    2 | 20                 |
|    3 | 200,500            |
+------+--------------------+
 
3 rows in set (0.00 sec)
 
3.2 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;
+------+----------------------------------+
| id   | group_concat(name separator ';') |
+------+----------------------------------+
|    1 | 10;20;20                         |
|    2 | 20                               |
|    3 | 200;500                          |
+------+----------------------------------+
 
3 rows in set (0.00 sec)
 
3.3 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;
 
+------+-----------------------------+
| id   | group_concat(distinct name) |
+------+-----------------------------+
|    1 | 10,20                       |
|    2 | 20                          |
|    3 | 200,500                     |
+------+-----------------------------+
 
3 rows in set (0.00 sec)
 
3.4 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;
 
+------+---------------------------------------+