SQL Server mode SQL

Question

I have a table that list students\' grades per class. I want a result set that looks like:

BIO...B
CHEM...C

Where the \"B\" and \"C\" are the m

Answer 1

Use a GROUP BY clause.

SELECT className, ClassMode(className)
FROM Grades
GROUP BY className

Your Mode() function would have to be created of course, but it would be a simple function like:

CREATE FUNCTION ClassMode(@ClassName varchar(50))
RETURNS varchar(2)
AS
BEGIN
    Declare @temp varchar(2)

    SELECT @temp = TOP 1 Grade, COUNT(*) Grades as frequency
    FROM Grades
    WHERE ClassName = @ClassName
    GROUP BY ClassName
    ORDER BY frequency DESC

    RETURN @temp
END

Answer 2

You just need to GROUP BY ClassName

SELECT ClassName, MODE(Grade) FROM YourTable GROUP BY ClassName

Answer 3

here, something like this on SQL 2005/2008:

;WITH 
  Counts AS (
    SELECT ClassName, Grade, COUNT(*) AS GradeFreq 
    FROM Scores
    GROUP BY ClassName, Grade
    )
, Ranked AS (
    SELECT ClassName, Grade, GradeFreq
    , Ranking = DENSE_RANK() OVER (PARTITION BY ClassName ORDER BY GradeFreq DESC)
    FROM Counts
    )
SELECT * FROM Ranked WHERE Ranking = 1

or perhaps just:

;WITH Ranked AS (
  SELECT 
    ClassName, Grade
  , GradeFreq = COUNT(*)
  , Ranking = DENSE_RANK() OVER (PARTITION BY ClassName ORDER BY COUNT(*) DESC)
  FROM Scores
  GROUP BY ClassName, Grade
  )
SELECT * FROM Ranked WHERE Ranking = 1