group_concat函数使用说明

MySQL中group_concat函数，能将相同的行组合起来。

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

Sql代码 收藏代码
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)

Sql代码 收藏代码
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

Java代码 收藏代码
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

Sql代码 收藏代码
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

Sql代码 收藏代码
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。

Sql代码 收藏代码
SELECT
EMPLOYEES.EMPID
,EMPLOYEES.EMPNAME
,DEPARTMENTS.DEPARTMENTNAME
,EMPLOYEES.DEPTID
,EMPLOYEES.EMPPWD
,EMPLOYEES.INSIDEEMAIL
,EMPLOYEES.OUTSIDEEMAIL
,EMPLOYEES.DELEFLAG
,EMPLOYEES.EMPCLASS
,(CONCAT(’[’, GROUP_CONCAT
(ROLE.Role_Name SEPARATOR ‘],[’), ‘]’)) AS ROLENAME
,(concat( ‘[’, (
SELECT
GROUP_CONCAT
(DEPARTMENTS.DEPARTMENTNAME separator ‘],[’)
FROM
EMP_ROLE_DEPT
LEFT JOIN DEPARTMENTS
ON (
DEPARTMENTS.DEPARTMENTID = EMP_ROLE_DEPT.DEPTID
AND DEPARTMENTS.DELEFLAG = 0
)
GROUP BY
EMP_ROLE_DEPT.EMPID
HAVING
EMP_ROLE_DEPT.EMPID = EMPLOYEES.EMPID
),’]’)) AS DEPARTMENTRIGHT
FROM
EMPLOYEES
LEFT JOIN DEPARTMENTS
ON (
DEPARTMENTS.DEPARTMENTID = EMPLOYEES.DEPTID
AND DEPARTMENTS.DELEFLAG = 0
)
LEFT JOIN ROLE_EMP
ON (ROLE_EMP.EMP_ID = EMPLOYEES.EMPID)
LEFT JOIN ROLE
ON (ROLE_EMP.ROLE_ID = ROLE.ROLE_ID)
GROUP BY
EMPLOYEES.EMPID

HAVING  
    EMPLOYEES.EMPID LIKE '%%'  
    AND EMPLOYEES.EMPNAME LIKE '%%'  
    AND EMPLOYEES.DELEFLAG = 0  
    AND (  
        EMPLOYEES.EMPCLASS = '1'  
        OR EMPLOYEES.EMPCLASS = '2'  
    )  
    AND EMPLOYEES.DEPTID = '001' LIMIT 0  
    ,16