Find Maximum Value in each Row – SQL Server

Here’s a simple and efficient way to find the maximum value in each row using SQL Server UNPIVOT

DECLARE @t table (id int PRIMARY KEY, col1 int, col2 int, col3 int)

-- SAMPLE DATA
INSERT INTO @t SELECT 1, 45, 2, 14
INSERT INTO @t SELECT 2, 8, 1, 12
INSERT INTO @t SELECT 3, 21, 20, 8
INSERT INTO @t SELECT 4, 8, 5, 2
INSERT INTO @t SELECT 5, 23, 49, 7
INSERT INTO @t SELECT 6, 19, 7, 5
INSERT INTO @t SELECT 7, 7, 7, 2
INSERT INTO @t SELECT 8, 14, 17, 2

-- QUERY
SELECT id, MAX(col) AS maxValue
FROM
(
  SELECT id, col FROM @t
  UNPIVOT
  (col FOR ListofColumns IN (col1,col2,col3))
   AS unpivott) AS p
GROUP BY id


OUTPUT

image


If you new to UNPIVOT, read Using PIVOT and UNPIVOT

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7 comments:

  1. D. TaylorFebruary 19, 2011 at 12:00 AM

    Simply brilliant. Can i find the highest and lowest value using any other approach than UNPIVOT. If you have the time, I just need this example for my knowledge

    ReplyDelete
  2. MadhivananFebruary 20, 2011 at 11:35 PM

    Taylor,

    Try this method

    select id, min(col1) as minValue, max(col1) as maxValue from
    (
    select id, col1 from @t
    union all
    select id, col2 from @t
    union all
    select id, col3 from @t
    ) as t
    group by id

    If you use version 2008, you can use values clause, refer point 3 in this post
    http://beyondrelational.com/blogs/madhivanan/archive/2010/08/02/values-clause-in-sql-server-2008.aspx

    ReplyDelete
  3. Suprotim AgarwalFebruary 21, 2011 at 2:34 AM

    Thanks Madhivanan. I too had written a query yesterday in response to this comment where I used CROSS APPLY. The advantage was using this, the OP can update existing columns if there's a need.

    http://www.sqlservercurry.com/2011/02/sql-server-highest-and-lowest-values-in.html

    ReplyDelete
  4. GopalFebruary 26, 2013 at 3:39 AM

    Excellent, great, useful.. Saved my 5 days effort and frustration..

    Awesome thinking, efficient method.

    Thanks so so so much :)

    ReplyDelete
  5. SQLGeekOctober 27, 2015 at 10:34 PM

    My question is to Madhivanan:
    First of all thanks for the solution given above.
    But adding to the above question if id column is not given, then how will we do it

    ReplyDelete
  6. UnknownOctober 27, 2015 at 10:59 PM

    This comment has been removed by the author.

    ReplyDelete
  7. AnonymousOctober 27, 2015 at 11:07 PM

    SQLGeek, if you do not have id column, you can use CASE expression

    select
    case
    when col1>col2 and col1>col3 then col1
    when col2>col3 then col2
    else col3
    end as maximum_value
    from table

    ReplyDelete