SQL查询根据同一表中其他列的值更新列

Question

Ok this is difficult to phrase, so here goes...

I am using MS SQL Server 2008 R2. I have a temp table that lets say has two already populated columns. There is a third empty column I want to populate based on the value of the first two columns. What I want to do is create a guid (using NEWUID()) for each matching combo of col1 and col2. Here is a visual example:

Lets say I have a temp table that looks like this initially:

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

I want it to get updated with new GUIDs so that it looks like this:

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

Notice how a new GUID is created for each matching pair. So the James/Running combo has the same GUID for all James/Running combos... and the John/Running also has the same GUID for the John/Running combos, but not the same GUID as the James/Running combos do.

I tried to make that as clear as possible, but hopefully that isn't clear as mud!

Can someone show me what the SQL query would look like in order to update that temp table with the correct GUIDs?

Thanks in advance.

Ryan

Answer 1

Using NEWID() seems to be a pain . Using it a CTE creates a sperate ID, so you need some intermediary table instead.

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 

Produces

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

Answer 2

I agree with @ConradFrix to use NEWID() first, Lamak script should be modified as mentioned below. It's working fine for me. Thanks for all.

WITH TableId AS
(
    SELECT DISTINCT Name, Activity, NEWID() SpecialId
    FROM YourTable
)
UPDATE A
SET A.SpecialId = B.SpecialId
FROM YourTable A
LEFT JOIN (SELECT Name, Activity, SpecialId FROM TableId) B
ON A.Name = B.Name AND A.Activity = B.Activity

Answer 3

I'm sure there are better ways to do this, but you can try the following:

WITH TableId AS
(
    SELECT DISTINCT Name, Activity
    FROM YourTable
)

UPDATE A
SET A.SpecialId = B.SpecialId
FROM YourTable A
INNER JOIN (SELECT Name, Activity, NEWID() SpecialId FROM TableId) B
ON A.Name = B.Name AND A.Activity = B.Activity

Answer 4

Well, I know that you're not using mySQL, but this is how it would work in mySQL (tested)

update temp_table, (
select uuid() as spec_key, name, activity from (
select distinct name, activity from temp_table) as anotherTemp) as anotheranotherTemp
set specialID = anotheranotherTemp.spec_key
where temp_table.Activity = anotheranotherTemp.activity 
and temp_table.Name = anotheranotherTemp.name;

It LOOKS like this would work in SQL 2008 (not-tested)

MERGE INTO temp_table AS tt
  USING      (
    select newId() as spec_key, name, activity from (
    select distinct name, activity from temp_table) as anotherTemp 
      ON   anotherTemp.activity       = tt.activity
      and anotherTemp.name = tt.name
WHEN MATCHED
  THEN UPDATE
    SET        specialID = anotherTemp.spec_key;

Performance would not be good though.