SQL Server下无限多级别分类查询解决办法(简单查询树形结构数据库表)

在开发中经常会遇到无限级分类的问题，最常见的是一些无限级目录之类的，如果你对SQL Server还不是太熟悉或者还不太熟悉SQL语言的话，这将是一件很困难的事情，也许你最后能实现类似的功能，不过可能花费的时间很长，效率也不是很理想，下面的示例也许能给你一个启示。

 

CREATE TABLE [dbo].[Tree] (
  [ID] [int] IDENTITY (1, 1) NOT NULL ,
  [PID] [int] NULL ,
 [Name] [varchar] (10) COLLATE Chinese_PRC_CI_AS NULL 
 ) ON [PRIMARY]
 GO
 
 CREATE  CLUSTERED  INDEX [IX_Tree] ON [dbo].[Tree]([PID]) ON [PRIMARY]
GO

ALTER TABLE [dbo].[Tree] WITH NOCHECK ADD 
CONSTRAINT [PK_Tree] PRIMARY KEY  NONCLUSTERED 
 (
     [ID]
 )  ON [PRIMARY] ,
 CONSTRAINT [子ID不能等于父ID] CHECK ([ID] <> [PID])
GO

ALTER TABLE [dbo].[Tree] ADD 
 CONSTRAINT [FK_Tree_Tree] FOREIGN KEY 
 (
 [PID]
 ) REFERENCES [dbo].[Tree] (
  [ID]
 )
GO

/**//****** 对象:  用户定义的函数 dbo.fGetTreeTable  ******/
CREATE FUNCTION dbo.fGetTreeTable
 (
 @ID int= null
 )
RETURNS @Tab TABLE(ID int, PID int, Name varchar(10), Lev int)
AS
 BEGIN
  Declare @lev int
  Set @lev=0
  
  While @lev=0 or @@ROWCount>0
  Begin
   Set @Lev=@Lev+1
   Insert @Tab(ID, PID, Name, Lev)
   Select ID, PID, Name, @Lev From Tree Where (@Lev=1 and ((PID=@ID) or (@ID is null and PID is null))) or (PID in (Select ID From @Tab Where Lev=@Lev-1))
   order by ID
  End
  RETURN
 END

GO

--实际数据
Insert Tree(PID, Name) values(null, 公司)
Insert Tree(PID, Name) values(3, IT)
Insert Tree(PID, Name) values(1, Fin)
Insert Tree(PID, Name) values(5, XZ)
Insert Tree(PID, Name) values(1, HR)
GO

 

 

直接查询Select * from dbo.fGetTreeTable(null)就可以输入所有记录。

评论

1 楼 w497480098h 2014-05-08  

学习了 很好谢谢