怎么实现3个表联合查询输出一个聚合表

[linjuming_phone]

具体问题请看我图片描述，实在没辙，求高手指点

途中 a,b,c 三个表 uid, gid 是固定字段，后面有个差异统计count字段，怎么用联合查询聚合成第四个表？

[nayi_224]

select coalesce(a.uid, b.uid, c.uid) uidd,
       coalesce(a.gid, b.gid, c.gid) gid,
       nvl(a.file_count, 0) file_count,
       nvl(b.reply_count, 0) reply_count,
       nvl(c.ask_count, 0) ask_count
  from a 
full join b
on a.uid = b.uid and a.gid = b.gid
full join c
on a.uid = c.uid and a.gid = c.gid
;