Sql 如何使用ORACLE按树计算组数？

现在我有一个这样的数据集；8项记录

这棵树的形状如下：

root -- 0
--child 100
  --sub child 108
     ---sub ...(maybe has more level)
--child 200
  --sub child 205
--child 400
  --sub child 423

select cid as node,count(1) as counts 
from (one subselect for get the 8 records) a 
start with a.pid = '0' 
connect by prior a.cid = a.pid) t group by cid;

我想计算所有的总和记录，每个子节点不是子节点，子节点的记录应该计算到它的父亲或祖父，直到第一级子节点

因此，结果应该是：

node    counts
100       5
200       1
400       2

但是当我使用start with connect by和with group by关键字时，我无法得到预期的结果

我的sql如下所示：

root -- 0
--child 100
  --sub child 108
     ---sub ...(maybe has more level)
--child 200
  --sub child 205
--child 400
  --sub child 423

select cid as node,count(1) as counts 
from (one subselect for get the 8 records) a 
start with a.pid = '0' 
connect by prior a.cid = a.pid) t group by cid;

结果为空。。 谁能帮我？或者，当与树结构一起使用时，谁知道oracle group by关键字的详细信息

试试这个：

SELECT top_cid, Count(1) FROM (
  WITH
    parent_child as (
      select distinct a.cid, a.pid from a
      union  
      select a.pid, 0 from a
      where a.pid<>0 and not exists (
        select 1 from a a1 where a1.cid=a.pid
      )
    ),
    tree as (
      select level as lvl,
        --connect_by_root in 10g and above
        replace(sys_connect_by_path(decode(level, 1, cid), '~'), '~') AS top_cid, 
        pid, cid 
      from parent_child
      start with pid = 0
      connect by prior cid = pid(+)
    )
  select tree.top_cid, a.pid, a.cid 
  from a, tree
  WHERE a.cid=tree.cid
) GROUP BY top_cid

---

您目前的查询结果如何？在group by子句中：group by aid，什么是aid？对不起，它应该是cid，结果为空。当数据集中没有400 0的条目时，-child 400怎么可能是根0的子项。数据集不是树表。它只是记录s的正常数据表。如果它不是树表，为什么需要连接方式？我得到的结果是：400-2，0-6不是除此之外的结果