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：

   1:  DECLARE @TT TABLE (ID int,Relation varchar(25),Name varchar(25),ParentID int)

   2:  INSERT @TT SELECT 1,' Great GrandFather' , 'Thomas Bishop', null  UNION ALL

   3:  SELECT 2,'Grand Mom', 'Elian Thomas Wilson' , 1  UNION ALL

   4:  SELECT 3, 'Dad', 'James Wilson',2 UNION ALL

   5:  SELECT 4, 'Uncle', 'Michael Wilson', 2 UNION ALL

   6:  SELECT 5, 'Aunt', 'Nancy Manor', 2 UNION ALL

   7:  SELECT 6, 'Grand Uncle', 'Michael Bishop', 1 UNION ALL

   8:  SELECT 7, 'Brother', 'David James Wilson',3 UNION ALL

   9:  SELECT 8, 'Sister', 'Michelle Clark', 3 UNION ALL

  10:  SELECT 9, 'Brother', 'Robert James Wilson', 3 UNION ALL

  11:  SELECT 10, 'Me', 'Steve James Wilson', 3

12:

  13:  ----------Query---------------------------------------

  14:  ;WITH FamilyTree

  15:  AS(

  16:    SELECT *, CAST(NULL AS VARCHAR(25)) AS ParentName, 0 AS Generation  FROM @TT

  17:      WHERE ParentID IS NULL

  18:      UNION ALL

  19:     SELECT Fam.*,FamilyTree.Name AS ParentName, Generation + 1   FROM @TT AS Fam

  20:        INNER JOIN FamilyTree    ON Fam.ParentID = FamilyTree.ID

  21:   )SELECT * FROM FamilyTree

Output:

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