Compare comma separated rows - sql

Question

I have a requirement where in I should compare top row with previous rows of database records which they are comma separated.
example :
My table data looks something like this:
ID Phase Updated By
1 Test1,Test2,Test3 sxmalla
2 Test1,Test2 rkgauta
3 Test1,Test3 sxmalla
I have to display somthing the most recent changes in Phase and who has updated.The comma seperated data is submitted with multiple chechboxes in front end. User can update them through multiple checkboxes in same page.
Here Test3 is most recent change,then below that Test2 is the most recent change and on third row the actual first entry.
I need to show the result as
Phase Updated By
Test3 sxmalla
Test2 rkgauta
Test1,Test3 sxmalla
Here is the code that I currently using to compare 2 comma seperated rows
ALTER Proc [dbo].[PMT_GetPhasesEditHistory]
#Project_ID int
As Begin
SET NOCOUNT ON
Declare #added varchar(1000), #removed varchar(1000),#strN varchar(1000),#strO varchar(1000)
DECLARE test_cursor CURSOR FOR
SET #strO=(SELECT TOP 1 P1.Phase from phase P1,Phase P2 where P1.ID = P2.ID-1 and p1.project_id=#Project_ID order by p1.ID Desc)
SET #strN =(SELECT TOP 1 P2.Phase from phase P1,Phase P2
where P1.ID = P2.ID-1 and p1.project_id=#Project_ID order by p1.ID Desc)
If object_id('dbo.#tN') is not null Begin ; drop table dbo.#tN ;End
CREATE TABLE dbo.#tN( var varchar(100)); insert into #tN select * from fnSplitStringAsTable(#strN,',')
If object_id('dbo.#tO') is not null Begin; drop table dbo.#tO ;End
CREATE TABLE dbo.#tO (var varchar(100)); insert into #tO select * from fnSplitStringAsTable(#strO,',')
Declare #i int
Set #i=1
Set #added = ''
While #i != (select COUNT(*)+1 from #tN)
Begin
if not exists(select VAR from #tO where var = (select Top 1 var from #tN where var in ( Select Top (#i) VAR from #tN where Var in (Select Top (#i) var From #tN order by VAR desc) order by var asc)))
Begin
Set #added = #added + (select Top 1 var from #tN where var in ( Select Top (#i) VAR from #tN where Var in (Select Top (#i) var From #tN order by VAR desc) order by var asc)) + ','
End
set #i=#i+1
End
If(len(#added) > 1) Begin; set #added = RTRIM(LEFT(#added,Len(#added) - 1)); End
Select #added as Added
drop table #tN;Drop table #tO
End

Answer 1

Here is a possible solution:
WITH CTE_Prep AS
(
SELECT *, DENSE_RANK() OVER (ORDER BY ID DESC) RN
FROM phase
CROSS APPLY dbo.DelimitedSplit8K(Phase,',')
)
,CTE_Result AS
(
SELECT ID, STUFF ((SELECT ', ' +Item
FROM CTE_Prep c WHERE Item NOT IN (SELECT Item FROM CTE_Prep c2 WHERE c2.RN + 1 = c.RN)
AND c.Id = c3.ID
FOR XML PATH('')),1,2,'') AS Phase
FROM CTE_Prep c3
GROUP BY ID
)
SELECT r.Phase, p.[Updated By] FROM CTE_Result r
LEFT JOIN phase p ON r.id = p.id
This is using DelimitedSplit8K function from SQLServerCentral for splitting, but I'm sure you can do with your existing.
SQLFiddle DEMO

Answer 2

I am going to try and answer the normalization question.
Table PhaseTest
PhaseID int
TestID int
PK PhaseID, TestID
(this PK will enforce no duplicate TestID in a PhaseID
Table PhaseUser
PhaseID int PK
UserID int
Table Test
TestID int PK
TestName varchar
Table User
UserID int PK
UserName varchar
this shows the results on separate lines (no comma)
select PT1.PhaseID, Test.TestName, User.UserName
from PhaseTest PT1
left outer join PhaseTest PT2
on PT2.PhaseID = PT1.PhaseID + 1
and PT2.TestID = PT1.TestID
join PhaseUser
on PhaseUser.UserID = PT1.UserID
join Test
on Test.TestID = PT1.UserID
where PT2.PhaseID is null
order by PT1.TestID
union
select PT1.PhaseID, Test.TestName, User.UserName
from PhaseTest PT1
join PhaseUser
on PhaseUser.UserID = PT1.UserID
join Test
on Test.TestID = PT1.UserID
where PT1.PhaseID = (select max(PhaseID) from PhaseTest)