Remove duplicate row and update next row to current row and continue - sql-server-2005

Question

I need a select query ..
Environment : SQL DBA -SQL SERVER 2005 or newer
Example :
In this sample table, if I select top 20 no duplicate records should come and next record should be in 20 records .
Example :
123456 should not repeat in 20 records and if 18th is duplicate, in place of 18th, 19th record should come and in 19th—20th should come, in 20th ---21st should come .
No concern of Asc or Desc for rows .
Lookup Table before
Id Name
123456 hello
123456 hello
123654 hi
123655 yes
LookUp Table after
Id Name
123456 hello
123654 hi
123655 yes
My table:
CREATE TABLE [dbo].[test](
[Id] [int] IDENTITY(1,1) NOT NULL,
[ContestId] [int] NOT NULL,
[PrizeId] [int] NOT NULL,
[ContestParticipantId] [int] NOT NULL,
[SubsidiaryAnswer] [varchar](256) NOT NULL,
[SubsidiaryDifference] [bigint] NOT NULL,
[AttemptTime] [datetime] NOT NULL,
[ParticipantName] [varchar](250) NOT NULL,
[IsSubscribed] [bit] NOT NULL,
[IsNewlyRegistered] [bit] NOT NULL,
[IsWinner] [bit] NOT NULL,
[IsWinnerConfirmed] [bit] NOT NULL,
[IsWinnerExcluded] [bit] NOT NULL) ON [PRIMARY]
My question is: from this select, we actually need the first 20, but unique ones.
SELECT TOP 20 * FROM test order by SubsidiaryDifference
When we do the above query, we have currently some double in there. In case there is a double, we need take them only 1 time and take the next one
Any one know this issue ?
Thanks in advance :)

Answer 1

Reading your question, it appears you don't really want to delete the rows from the table - you just want to display the TOP 20 distinct rows - you try something like this:
;WITH LastPerContestParticipantId AS
(
SELECT
ContestParticipantId,
-- add whatever other columns you want to select here
ROW_NUMBER() OVER(PARTITION BY ContestParticipantId
ORDER BY SubsidiaryDifference) AS 'RowNum'
FROM dbo.Test
)
SELECT TOP (20)
ContestParticipantId,
-- add whatever other columns you want to select here
SubsidiaryDifference
FROM
LastPerContestParticipantId
WHERE
RowNum = 1
This will show you the most recent row for each distinct ContestParticipantId, order by SubsidiaryDifference - try it!
Update #2: I've created a quick sample - it uses the data from your original post - plus an additional SubID column so that I can order rows of the same ID by something...
When I run this with my CTE query, I do get only one entry for each ID - so what exactly is "not working" for you?
DECLARE #test TABLE (ID INT, EntryName VARCHAR(50), SubID INT)
INSERT INTO #test
VALUES(123456, 'hello', 1), (123456, 'hello', 2), (123654, 'hi', 1), (123655, 'yes', 3)
;WITH LastPerId AS
(
SELECT
ID, EntryName,
ROW_NUMBER() OVER(PARTITION BY ID ORDER BY SubID DESC) AS 'RowNum'
FROM #test
)
SELECT TOP (3)
ID, EntryName
FROM
LastPerId
WHERE
RowNum = 1
Gives an output of:
ID EntryName
123456 hello
123654 hi
123655 yes
No duplicates.