Updaing using ROW_NUMBER()

  • Let's just say I have a table with columns ID and Name that looks like:

    [font="Courier New"]ID Name



    03 Bill






    09 Ted



    12 [/font]

    I want to update rows 1-2 & 4-6 with the Name Bill

    and 7-8 & 10-12 with the Name Ted.

    the update will always be an update to two prior and three subsequent rows where there is a non-null entry in column [Name]

    This is easy enough to do in an RBAR fashion but not efficient but I'm not interested in that.

    How could I achieve this using ROW_NUMBER()

    Thank you in advance


    (Updaning??? must be a new command, meant updating, sorry)

  • You don't need ROW_NUMBER here:

    declare @table table (ID int, Name varchar(100))

    insert @table select 1,null

    insert @table select 2,null

    insert @table select 3,'Bill'

    insert @table select 4,null

    insert @table select 5,null

    insert @table select 6,null

    insert @table select 7,null

    insert @table select 8,null

    insert @table select 9,'Ted'

    insert @table select 10,null

    insert @table select 11,null

    insert @table select 12,null

    UPDATE u

    SET u.Name = n.Name

    FROM @table u

    CROSS APPLY(SELECT TOP 1 t.Name FROM @table t


    AND ( t.ID - u.ID between 1 AND 2

    OR u.ID - t.ID between 1 AND 3)) n

    WHERE u.Name IS NULL

    SELECT * FROM @table

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  • Thank you for the quick response. The example you provided works great. So I've tweaked it to update my test table which has about 2.5million rows. It's been running for 10 minutes and counting. The estimated execution plan looked ok and it was making use of available indexes. I'll post up the results when it completes.

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