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.