PostgreSQL中array_to_string函数来将数组转换成逗号分隔的字符串

array_agg函数用于将多个行的值聚合为一个数组。

默认情况下，array_agg生成的数组会被包含在大括号{}中。如果你想去掉这些括号，

可以使用array_to_string函数来将数组转换成逗号分隔的字符串

select user_ids, array_to_string(user_names, ',') ,id,hd_number,hd_name from (

         SELECT

        b.commissioner as user_ids, array_agg(t.user_name) as user_names ,

        b.id,b.hd_number,b.hd_name

        FROM _info b

        LEFT JOIN _user t ON t.user_id = ANY ( STRING_TO_ARRAY(         b.commissioner, ',' ) )

GROUP BY b.id

) tt