递归SQL函数 [英] Recursive SQL Function
问题描述
我有两个表,我需要编写一个递归函数.
Hi,
I have two tables and I need to write a recursive function.
PRODUCT with columns
PRODUCT_ID varchar(50), PRIMARYKEY and
PRODUCT_GROUP_ID varchar (200)
PRODUCT_GROUP with columns
PRODUCT_GROUP_ID varchar(50), PRIMARY KEY and
PRODUCT_UPPER_GROUP_ID varchar (200)
这是PRODUCT表的数据:
Here is data for PRODUCT table:
PRODUCT_ID PRODUCT_GROUP_ID
SonyTFT3500 SonySiyah
这是PRODUCT_GROUP表的数据:
and here is the data for PRODUCT_GROUP table:
PRODUCT_GROUP_ID PRODUCT_UPPER_GROUP_ID
Elektronik, null
Ev Elektroniği, Elektronik
TV, Ev Elektroniği
Sony, TV
SonySiyah, Sony
除Elektronik之外,所有其他PRODUCT_GROUP_IDs
都有一个上层节点.我需要的是给定PRODUCT_ID = ''SonyTFT3500''
的函数,该函数返回类似以下内容的内容:
Except Elektronik, all the other PRODUCT_GROUP_IDs
have an upper node. What I need is a function given a PRODUCT_ID = ''SonyTFT3500''
which returns something like this:
temp = "Elektronik > Ev Elektroniği > TV > Sony > SonySiyah".
temp2 = "Elektronik > Ev Elektroniği > TV > Sony > SonySiyah > subnode > subnode > .. > ... > ...."
您可以将PRODUCT_GROUP_ID
视为一个父类别,该类别可能具有一个类别,并且类别可能具有一个子类别,并且该子类别具有其自己的子类别,并且无限期地像这样.
如何在Sql Server 2008中编写递归函数,以便获得此字符串temp?
You can think of PRODUCT_GROUP_ID
as a parentcategory which might have a category and category might have a subcategory and subcategory has its own subcategory and this goes like this indefinitely.
How do I write a recursive function in Sql Server 2008 so that I get this string temp ?
推荐答案
看看通用表表达式(CTE)
与common_table_expression(Transact-SQL) [ http://www.4guysfromrolla.com/webtech/071906-1.shtml [ ^ ]
完成后,您应该可以轻松解决问题.
问候
Espen Harlinn
Take a look at Common Table Expressions (CTE)
WITH common_table_expression (Transact-SQL)[^]
http://www.4guysfromrolla.com/webtech/071906-1.shtml[^]
When you are done, you should be able to easily solve your problem.
Regards
Espen Harlinn
CREATE FUNCTION [dbo].[GetUpperProductNode]
(
@PRODUCT_GROUP_ID NVARCHAR(100)
)
RETURNS NVARCHAR(100)
AS
BEGIN
DECLARE @PRODUCT_UPPER_GROUP_ID NVARCHAR(100)
SELECT @PRODUCT_UPPER_GROUP_ID = PRODUCT_UPPER_GROUP_ID FROM PRODUCT_GROUP WHERE PRODUCT_GROUP_ID = @PRODUCT_GROUP_ID
RETURN @PRODUCT_UPPER_GROUP_ID
END
DECLARE @ReachedTop BIT
SET @ReachedTop = 0
CREATE TABLE #Result (PRODUCT_UPPER_GROUP_ID NVARCHAR(100))
DECLARE @PRODUCT_UPPER_GROUP_ID NVARCHAR(100)
SET @PRODUCT_UPPER_GROUP_ID = 'SonySiyah'
INSERT #Result SELECT @PRODUCT_UPPER_GROUP_ID
WHILE (@ReachedTop = 0)
BEGIN
PRINT @PRODUCT_UPPER_GROUP_ID
SET @PRODUCT_UPPER_GROUP_ID = (SELECT dbo.GetUpperProductNode(@PRODUCT_UPPER_GROUP_ID))
IF (@PRODUCT_UPPER_GROUP_ID IS NULL)
SET @ReachedTop = 1
ELSE
INSERT #Result SELECT @PRODUCT_UPPER_GROUP_ID
END
SELECT * FROM #Result
DROP TABLE #Result
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