Question

我有一个oracle表包含和ID列，ID_child列和几个事实字段。我知道一个ID，我想找到它的顶级父母。我知道的id会放入ID_child字段，ID就是它的父节点。这个查询有效，但我只得到一行，我可以用常规的SQL查询。 如何获取热门ID？

SELECT
item_tbl.id, item_tbl.id_child
FROM item_tbl
START WITH item_tbl.id_child = 12510646
CONNECT BY PRIOR item_tbl.id_child = item_tbl.id

我得到的结果：

ID               ID_CHILD
12512162         12510646

Answer 1

例如：事物的连接顺序;父母需要在左侧。

With item_tbl (ID, ID_CHILD) as 
(SELECT 1,2 from dual UNION ALL
SELECT 2,3 from dual UNION ALL
SELECT 3,4 from dual)
SELECT
item_tbl.id, item_tbl.id_child, level
FROM item_tbl
START WITH item_tbl.id_child = 4
CONNECT BY PRIOR item_tbl.id= item_tbl.id_child
Order by level desc;

Answer 2

如何获得最高ID？

您可以使用CONNECT_BY_ISLEAF伪列：

SELECT id, id_child
FROM   item_tbl
WHERE  CONNECT_BY_ISLEAF = 1
START WITH id_child = 12510646
CONNECT BY PRIOR id = id_child

如果这不起作用，请尝试交换CONNECT BY子句中的术语。

oracle sql查询hierarchyicle查询查找顶级

2 个答案: