group_concat函数详解

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'])

基本查询

1. select * from

select * from aa;

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

以id分组，把name字段的值打印在一行，逗号分隔(默认)

1. select id,group_concat(name) from aa group by

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)

以id分组，把name字段的值打印在一行，分号分隔

1. select id,group_concat(name separator ';') from aa group by id;  

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)

以id分组，把去冗余的name字段的值打印在一行，

逗号分隔

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

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)

以id分组，把name字段的值打印在一行，逗号分隔，以name排倒序

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

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)

测试sql，项目中用到的。

1. SELECT
2.         EMPLOYEES.EMPID   
3.         ,EMPLOYEES.EMPNAME   
4.         ,DEPARTMENTS.DEPARTMENTNAME   
5.         ,EMPLOYEES.DEPTID   
6.         ,EMPLOYEES.EMPPWD   
7.         ,EMPLOYEES.INSIDEEMAIL   
8.         ,EMPLOYEES.OUTSIDEEMAIL   
9.         ,EMPLOYEES.DELEFLAG   
10.         ,EMPLOYEES.EMPCLASS   
11. '[', <SPAN style="COLOR: #ff0000">GROUP_CONCAT</SPAN>   
12. (ROLE.Role_Name SEPARATOR '],['), ']')) AS
13. '[', (   
14. SELECT
15. "COLOR: #ff0000">GROUP_CONCAT</SPAN>   
16. (DEPARTMENTS.DEPARTMENTNAME separator '],[')   
17. FROM
18.                     EMP_ROLE_DEPT   
19. LEFT JOIN
20. ON
21.                                 DEPARTMENTS.DEPARTMENTID = EMP_ROLE_DEPT.DEPTID   
22. AND
23.                             )   
24. GROUP BY
25.                     EMP_ROLE_DEPT.EMPID   
26. HAVING
27.                     EMP_ROLE_DEPT.EMPID = EMPLOYEES.EMPID   
28. ']')) AS
29. FROM
30.         EMPLOYEES   
31. LEFT JOIN
32. ON
33.                     DEPARTMENTS.DEPARTMENTID = EMPLOYEES.DEPTID   
34. AND
35.                 )   
36. LEFT JOIN
37. ON
38. LEFT JOIN
39. ON
40. <SPAN style="COLOR: #ff0000">    GROUP BY
41.         EMPLOYEES.EMPID</SPAN>   
42.   
43. HAVING
44. LIKE '%%'
45. AND EMPLOYEES.EMPNAME LIKE '%%'
46. AND
47. AND
48. '1'
49. OR EMPLOYEES.EMPCLASS = '2'
50.         )   
51. AND EMPLOYEES.DEPTID = '001'
52.         ,16