help to get first occurrence value when the value is duplicated

  • Hello,

    would someone help me to generate output as specified below. i need to get 1st value when record is duplicated in hierarchyval column

    IF OBJECT_ID('tempdb..#test') IS NOT NULL

    drop table #test

    create table #test

    (

    hierarchyid int

    ,hierarchyval int

    )

    insert into #test

    values (1,30005)

    , (2,30005)

    ,(3,30005)

    ,(4,30031)

    ,(5,30031)

    ,(6,30031)

    ,(7,30031)

    ,(8,30033)

    ,(9,30037)

    ,(10,30086)

    ,(11,30086)

    ,(12,30086)

    ,(13,30086)

    ,(14,30086)

    ,(15,30156)

    ,(16,30156)

    ,(17,30400)

    ,(18,30400)

    ,(19,30402)

    ,(20,30402)

    ,(21,30403)

    ,(22,30403)

    ,(23,31194)

    ,(24,31194)

    ,(25,31194)

    ,(26,31194)

    ,(27,82832)

    ,(28,82832)

    ,(29,82832 )

    o/p should be as below

    select * from #test

    where hierarchyid in (

    1,4,8,9,10,15,17,19,21,23,28)

  • This should do it:

    with cte as

    (

    Select hierarchyid, hierarchyval,

    row_number() over(Partition by hierarchyval order by hierarchyid) RowNum

    from #test

    )

    select * from cte

    where rownum = 1

    __________________________________________________________________________________________________________
    How to Post to get the most: http://www.sqlservercentral.com/articles/Best+Practices/61537/

  • I like the use of CTE but could you not get the same result by simply using:

    select min(hierarchyid) hierarchyid, hierarchyval from #test

    group by hierarchyval

    Just seems a tad easier?

    ...

  • Another quick solution

    😎

    SELECT

    MIN(T.hierarchyid) AS [hierarchyid]

    ,T.hierarchyval

    FROM #test T

    GROUP BY T.hierarchyval;

    The two solutions posted are close in performance or rather lack there of, if no supporting indices exist, i.e. Partition-Order-Covering or GroupBy-Order-Covering, see the example below.

    USE tempdb;

    GO

    SET NOCOUNT ON;

    IF OBJECT_ID('tempdb..#test') IS NOT NULL

    drop table #test

    create table #test

    (

    hierarchyid int NOT NULL

    ,hierarchyval int NOT NULL

    );

    insert into #test (hierarchyid,hierarchyval)

    values ( 1 ,30005)

    ,( 2 ,30005)

    ,( 3 ,30005)

    ,( 4 ,30031)

    ,( 5 ,30031)

    ,( 6 ,30031)

    ,( 7 ,30031)

    ,( 8 ,30033)

    ,( 9 ,30037)

    ,(10 ,30086)

    ,(11 ,30086)

    ,(12 ,30086)

    ,(13 ,30086)

    ,(14 ,30086)

    ,(15 ,30156)

    ,(16 ,30156)

    ,(17 ,30400)

    ,(18 ,30400)

    ,(19 ,30402)

    ,(20 ,30402)

    ,(21 ,30403)

    ,(22 ,30403)

    ,(23 ,31194)

    ,(24 ,31194)

    ,(25 ,31194)

    ,(26 ,31194)

    ,(27 ,82832)

    ,(28 ,82832)

    ,(29 ,82832);

    /* Heap */

    SELECT

    MIN(T.hierarchyid) AS [hierarchyid]

    ,T.hierarchyval

    FROM #test T

    GROUP BY T.hierarchyval;

    ;with cte as

    (

    Select hierarchyid, hierarchyval,

    row_number() over(Partition by hierarchyval order by hierarchyid) RowNum

    from #test

    )

    select * from cte

    where rownum = 1

    ;

    /* Clustered Index */

    ALTER TABLE #test ADD CONSTRAINT PK_TEST_BOTH_COLS PRIMARY KEY CLUSTERED (hierarchyval ASC,hierarchyid ASC);

    SELECT

    MIN(T.hierarchyid) AS [hierarchyid]

    ,T.hierarchyval

    FROM #test T

    GROUP BY T.hierarchyval;

    ;with cte as

    (

    Select hierarchyid, hierarchyval,

    row_number() over(Partition by hierarchyval order by hierarchyid) RowNum

    from #test

    )

    select * from cte

    where rownum = 1

    ;

    /* Unique nonclustered index */

    CREATE UNIQUE NONCLUSTERED INDEX UNQNCLIDX_TMP_TEST_POC ON #test (hierarchyval ASC,hierarchyid ASC);

    SELECT

    MIN(T.hierarchyid) AS [hierarchyid]

    ,T.hierarchyval

    FROM #test T

    GROUP BY T.hierarchyval;

    ;with cte as

    (

    Select hierarchyid, hierarchyval,

    row_number() over(Partition by hierarchyval order by hierarchyid) RowNum

    from #test

    )

    select * from cte

    where rownum = 1

    ;

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