SQL---SQL recursion

sql recursion

1,use function

 

代码

   
     

    
      
    
      Create
    
       
    
      function
    
       
    
      [
    
      dbo
    
      ]
    
      .
    
      [
    
      GetChild
    
      ]
    
      (
    
      @ID
    
       
    
      varchar
    
      (
    
      10
    
      ))

    
      returns
    
       
    
      @t
    
       
    
      table
    
      (ID 
    
      varchar
    
      (
    
      10
    
      ),ParentID 
    
      varchar
    
      (
    
      10
    
      ),
    
      Level
    
       
    
      int
    
      )

    
      as
    
      

    
      begin
    
      
 
    
      declare
    
       
    
      @i
    
       
    
      int
    
      
 
    
      set
    
       
    
      @i
    
       
    
      =
    
       
    
      1
    
      
 
    
      insert
    
       
    
      into
    
       
    
      @t
    
       
    
      select
    
       
    
      @ID
    
      ,
    
      @ID
    
      ,
    
      0
    
       
 
    
      insert
    
       
    
      into
    
       
    
      @t
    
       
    
      select
    
       ID,ParentID,
    
      @i
    
       
    
      from
    
       Dept 
    
      where
    
       ParentID 
    
      =
    
       
    
      @ID
    
      

 
    
      while
    
       
    
      @@rowcount
    
      <>
    
      0
    
      
 
    
      begin
    
      
 
    
      set
    
       
    
      @i
    
       
    
      =
    
       
    
      @i
    
       
    
      +
    
       
    
      1
    
      
 
    
      insert
    
       
    
      into
    
       
    
      @t
    
      
 
    
      select
    
      
 a.ID,a.ParentID,
    
      @i
    
      
 
    
      from
    
      
 Dept a,
    
      @t
    
       b
 
    
      where
    
      
 a.ParentID
    
      =
    
      b.ID 
    
      and
    
       b.
    
      Level
    
       
    
      =
    
       
    
      @i
    
      -
    
      1
    
      
 
    
      end
    
      
 
    
      return
    
      

    
      end
   
     

 

 

2,use the feature of sql 2005

 

 

代码

   
     

    
      
    
      Declare
    
       
    
      @Id
    
       
    
      Int
    
       

    
      Set
    
       
    
      @Id
    
       
    
      =
    
       
    
      24
    
      ; 


    
      With
    
       RootNodeCTE(Id,ParentId) 

    
      As
    
       
( 

    
      Select
    
       Id,ParentId 
    
      From
    
       Dept 
    
      Where
    
       ParentId 
    
      In
    
       (
    
      @Id
    
      ) 

    
      Union
    
       
    
      All
    
       

    
      Select
    
       Dept.Id,Dept.ParentId 
    
      From
    
       RootNodeCTE 

    
      Inner
    
       
    
      Join
    
       Dept

    
      On
    
       RootNodeCTE.Id 
    
      =
    
       Dept.ParentId 
) 


    
      Select
    
       
    
      *
    
       
    
      From
    
       RootNodeCTE