sql树形查询

sql:

使用Common As：递归公用表

https://docs.microsoft.com/en-us/sql/t-sql/queries/with-common-table-expression-transact-sql?view=sql-server-2017

sql：http：//blog.51cto.com/tianxingzhe/1720092

/****** Script for SelectTopNRows command from SSMS  ******/

--查询某个节点上的所有父节点  如果需要过滤在where后面跟过滤条件
WITH MyTest
AS (
   --起始条件
   SELECT id,
          title,
          parent
   FROM tb_menu
   WHERE id = 44 --列出子节点查询条件
   UNION ALL --http://www.w3school.com.cn/sql/sql_union.asp
   --递归条件
   SELECT a.id,
          a.title,
          a.parent
   FROM tb_menu a
       INNER JOIN MyTest b --执行递归，这里就要理解下了
           ON a.id = b.parent)
SELECT *
FROM MyTest;

--查询父节点下面的子节点
WITH cte_child (id, title, parent, level)
AS (
   --起始条件
   SELECT id,
          title,
          parent,
          0 AS level
   FROM tb_menu
   WHERE id = 6 --列出父节点查询条件
   UNION ALL
   --递归条件
   SELECT a.id,
          a.title,
          a.parent,
          b.level + 1
   FROM tb_menu a
       INNER JOIN cte_child b
           ON (a.parent = b.id))
SELECT *
FROM cte_child;

Oracle的树形：

Oracle:https://blog.csdn.net/u014421556/article/details/51689787

Oracle树查询的最重要的就是select...start with... connect by...prior语法了。

--列出父节点的所有子节点<font></font>
SELECT *<font></font>
  FROM VD_REGIONAL vr START WITH ID = '0358DEF3091E6E9AE0503F0A05020A18' CONNECT BY vr.PARENT_ID = PRIOR vr.ID;

--列出子节点的所有父节点    不要顶级父类  [WHERE vr.PARENT_ID!='0']<font></font>
SELECT *
  FROM VD_REGIONAL vr  START WITH ID = '2c90898b63f968f40163fc31b37c08d3' CONNECT BY vr.ID = PRIOR vr.PARENT_ID;
  --条件筛选
  SELECT *
  FROM VD_REGIONAL vr  WHERE vr.PARENT_ID!='' START WITH ID = '2c90898b63f968f40163fc31b37c08d3' CONNECT BY vr.ID = PRIOR vr.PARENT_ID;