HIVE SQL实现分组字符串拼接concat

在Mysql中可以通过group_concat()函数实现分组字符串拼接，在HIVE SQL中可以使用concat_ws()+collect_set()/collect_list()函数实现相同的效果。
实例：

a	b	c
2014	B	9
2015	A	8
2014	A	10
2015	B	7
2014	B	6

1.concat_ws+collect_list 非去重拼接

select a ,concat_ws('-',collect_list(b))  as col_b,concat_ws('-',collect_list(cast(c as string)))  as col_c
from tb_name
group by a
;

查询结果：

a	col_b	col_c
2014	B-A-B	9-10-6
2015	A-B	8-7

2.concat_ws+collect_set 去重拼接

select a ,concat_ws('-',collect_set(b))  as col_b,concat_ws('-',collect_set(cast(c as string)))  as col_cfrom tb_name
group by a
;

查询结果：

a	col_b	col_c
2014	B-A	9-10-6
2015	A-B	8-7

3.如果在分组拼接的时候需要保持拼接结果为有序排序，可以通过以下两种方式
1）先排序再拼接

select a ,concat_ws('-',collect_set(b))  as col_b,concat_ws('-',collect_set(cast(c as string)))  as col_cfrom 
(
select a ,b,c,row_number() over (partition by a order by b asc) as rn
from tb_name
) t
group by a
;

查询结果：

a	col_b	col_c
2014	A-B	10-6-9
2015	A-B	8-7

select a ,concat_ws('-',collect_list(b))  as col_b,concat_ws('-',collect_list(cast(c as string)))  as col_cfrom 
(
select a ,b,c,row_number() over (partition by a order by b asc) as rn
from tb_name
) t
group by a
;

查询结果：(col_b与col_c 的位置对应且col_b中的字符有序)

a	col_b	col_c
2014	A-B-B	10-6-9
2015	A-B	8-7

2）sort_array（）函数升序排列

select a ,concat_ws('-',sort_array(collect_list(b)))  as col_bfrom tb_name
group by a
;

a	col_b
2014	A-B-B
2015	A-B