GROUP_CONCAT为MySQL提供的函数，MaxCompute对应为wm_concat。
数据： table t (a,b) a b c
zhang 1 10 wang 2 20 wang 3 30 guo 6 60 wang 2 30
场景一.将a进行合并，不去重
代码语言：javascript复制MySQL:
select a, group_concat(b) from t group by a;
MaxCompute:
select a, wm_concat(',', b) as b from t group by a;|a| b |
|zhang|1| |wang | 2,3,2| |guo | 6 |
场景二.将a进行合并，去重
代码语言：javascript复制MySQL:
select a, group_concat(distinct b) from t group by a;
MaxCompute:
select a, wm_concat(distinct ',', b) as b from t group by a;|a| b |
|zhang|1| |wang | 2,3| |guo | 6 |
场景三.将a进行合并且排序，不去重
代码语言：javascript复制MySQL:
select a, group_concat(b order by b desc)
from t
group by a;
MaxCompute:
select a, wm_concat(',', b) as b
from (select a, b from t order by a, b desc)
group by a;|a| b |
|zhang|1| |wang | 2,2,3| |guo | 6 |
场景四.将a进行合并且排序，去重
代码语言：javascript复制MySQL:
select a, group_concat(distinct b order by b desc) from t
group by a;
MaxCompute:
select a, wm_concat(',', b) as b
from (
select distinct a, b
from t
order by a, b asc)
group by a;|a| b |
|zhang|1| |wang | 2,3| |guo | 6 |
场景五.将b、c进行合并
代码语言：javascript复制MySQL:
select a, group_concat(concat_ws(':', b, c))
from t
group by a;
MaxCompute:
(1).
select a, wm_concat(',', concat_ws(':',b,c)) as b from t
group by a;
(2).
select a, wm_concat(',', concat(b,':',c))
from t group by a;|a| b |
|zhang|1:10| |wang | 1:20,2:30,3:30 | |guo | 6:60 |
