SQL Query根据同一个表中其他列的值更新列

Question

好的,这很难说,所以这里......

我正在使用MS SQL Server 2008 R2.我有一个临时表,可以说有两个已经填充的列.我想根据前两列的值填充第三个空列.我想要做的是为col1和col2的每个匹配组合创建一个guid(使用NEWUID()).这是一个视觉示例:

让我说我有一个最初看起来像这样的临时表:

Name    Activity    SpecialId
James   Running     
James   Running
James   Walking
John    Running
John    Running
John    Walking

我想让它更新新的GUID,使它看起来像这样:

Name    Activity    SpecialId
James   Running     SOMEFAKEGUID_1
James   Running     SOMEFAKEGUID_1
James   Walking     SOMEFAKEGUID_2
John    Running     SOMEFAKEGUID_3
John    Running     SOMEFAKEGUID_3
John    Walking     SOMEFAKEGUID_4

请注意如何为每个匹配对创建新的GUID.因此,James/Running组合对所有James/Running组合具有相同的GUID ...而John/Running也具有与John/Running组合相同的GUID,但与James/Running组合的GUID不同.

我试图尽可能清楚地表明这一点,但希望这不是很清楚!

有人可以告诉我SQL查询会是什么样子,以便使用正确的GUID更新临时表吗？

提前致谢.

瑞安

Answer 1

使用 NEWID()似乎很痛苦。使用它，CTE 会创建一个单独的 ID，因此您需要一些中间表。

Declare @Table as table (name varchar(20), activity varchar(20) , SpecialID uniqueidentifier)
Declare @DistinctTable as table (name varchar(20), activity varchar(20) , SpecialID uniqueidentifier)

INSERT INTO @Table 
(name, activity)
values
('James','Running'),    
('James','Running'),
('James','Walking'),
('John','Running'),
('John','Running'),
('John','Walking')



WITH distinctt 
     AS (SELECT DISTINCT name, 
                         activity 
         FROM   @Table) 
INSERT INTO @DistinctTable 
SELECT name, 
       activity, 
       Newid() 
FROM   distinctt 

UPDATE @Table 
SET    specialid = dt.specialid 
FROM   @Table t 
       INNER JOIN @DistinctTable dt 
         ON t.activity = dt.activity 
            AND t.name = dt.name 

SELECT * FROM @Table 

生产

name                 activity             SpecialID
-------------------- -------------------- ------------------------------------
James                Running              AAA22BC5-51FE-43B3-8CC9-4C4A5B4CC981
James                Running              AAA22BC5-51FE-43B3-8CC9-4C4A5B4CC981
James                Walking              1722B76B-5F17-4931-8D7C-2ECADB5A4DFD
John                 Running              FBC1F86B-592D-4D30-ACB3-80DA26B00900
John                 Running              FBC1F86B-592D-4D30-ACB3-80DA26B00900
John                 Walking              84282844-AAFD-45CA-9218-F7933E5102C6