PostgreSql 合并多行记录

需求描述：

A表有如下数据

id

1

2

3

4

B表有如下数据

id	name
1	aaa
1	bbb
1	ccc
2	aa
2	bb
3	c

 

A表和B表通过id关联，需要查询结果如下：

id	name
1	aaa,bbb,ccc
2	aa,bb
3	c
4

查询语句如下：

SELECT a.id,array_to_string(array(    
   SELECT b.name  FROM  db_xx."B" b  WHERE b.id=a.id     
 ), ',') as name  
from db_xx."A" a  
order by a.id
SELECT a.id,array_to_string(array(
   SELECT b.name  FROM  db_xx."B" b  WHERE b.id=a.id
 ), ',') as name
from db_xx."A" a
order by a.id