使用SQL SERVER 2005/2008 递归CTE查询树型结构

       我们经常遇到树型结构，把它们显示在一个类似TreeView控件上的情况。这时我们可以使用Recursive Common Table Expressions(CTE)实现。下面是一个简单的Family Tree 示例：

DECLARE @TT TABLE (ID int,Relation varchar(25),Name varchar(25),ParentID int)
INSERT @TT SELECT 1,' Great GrandFather' , 'Thomas Bishop', null  UNION ALL
SELECT 2,'Grand Mom', 'Elian Thomas Wilson' , 1  UNION ALL
SELECT 3, 'Dad', 'James Wilson',2 UNION ALL
SELECT 4, 'Uncle', 'Michael Wilson', 2 UNION ALL
SELECT 5, 'Aunt', 'Nancy Manor', 2 UNION ALL
SELECT 6, 'Grand Uncle', 'Michael Bishop', 1 UNION ALL
SELECT 7, 'Brother', 'David James Wilson',3 UNION ALL
SELECT 8, 'Sister', 'Michelle Clark', 3 UNION ALL
SELECT 9, 'Brother', 'Robert James Wilson', 3 UNION ALL
SELECT 10, 'Me', 'Steve James Wilson', 3

----------Query---------------------------------------
;WITH FamilyTree
AS(
  SELECT *, CAST(NULL AS VARCHAR(25)) AS ParentName, 0 AS Generation  FROM @TT
    WHERE ParentID IS NULL
    UNION ALL
   SELECT Fam.*,FamilyTree.Name AS ParentName, Generation + 1   FROM @TT AS Fam
      INNER JOIN FamilyTree    ON Fam.ParentID = FamilyTree.ID
 )SELECT * FROM FamilyTree

Output:

希望对您有帮助

Author: Petter Liu    http://www.cnblogs.com/wintersun