The multi-part identifier could not be bound error on a function with cursor inside

Question

I have a function which takes student id as input and returns the average grade of the student.

I'm not sure why I'm getting this bound error. Is it because of the FETCH next command?

The CourseEnrollment table has 2 columns, studentid, courseid and finalgrade

CREATE FUNCTION dbo.PersonalAverage ( @StudentId VARCHAR(20) )

    RETURNS DECIMAL AS

    BEGIN

        DECLARE @AverageGrade DECIMAL(5,2)
        DECLARE @TotalMarks INT
        DECLARE @NumberOfCourses INT

        SET @AverageGrade=0
        SET @TotalMarks=0
        SET @NumberOfCourses=0


        DECLARE CalculateAverage CURSOR FOR
        SELECT FinalGrade 
            FROM CourseEnrollment
                WHERE @StudentId=dbo.CourseEnrollment.StudentId

        OPEN CalculateAverage 

        WHILE @@FETCH_STATUS=0

        BEGIN

            SET @NumberOfCourses = @NumberOfCourses + 1
            SET @TotalMarks = @TotalMarks + dbo.CourseEnrollment.FinalGrade

            FETCH NEXT FROM CalculateAverage INTO @TotalMarks
        END


        IF @NumberOfCourses>0

        BEGIN
            SET @AverageGrade = @TotalMarks/@NumberOfCourses
        END


        CLOSE CalculateAverage
        DEALLOCATE Calculateaverage


         RETURN @AverageGrade



    END;

Corrected Version:

CREATE FUNCTION dbo.PersonalAverage ( @StudentId VARCHAR(20) )

    RETURNS DECIMAL(5,2) AS

    BEGIN

        DECLARE @FinalGrade INT
        DECLARE @AverageGrade DECIMAL(5,2)
        DECLARE @TotalMarks DECIMAL(5,2)
        DECLARE @NumberOfCourses INT

        SET @AverageGrade=0
        SET @TotalMarks=0
        SET @NumberOfCourses=0
        SET @FinalGrade=0


        DECLARE CalculateAverage CURSOR FOR
        SELECT dbo.CourseEnrollment.FinalGrade 
            FROM dbo.CourseEnrollment
                WHERE @StudentId=dbo.CourseEnrollment.StudentId AND dbo.CourseEnrollment.FinalGrade IS NOT NULL

        OPEN CalculateAverage 

        FETCH NEXT FROM CalculateAverage INTO @FinalGrade 

        WHILE @@FETCH_STATUS = 0

        BEGIN

            SET @NumberOfCourses = @NumberOfCourses + 1
            SET @TotalMarks = @TotalMarks + @FinalGrade

            FETCH NEXT FROM CalculateAverage INTO @FinalGrade
        END


        IF @NumberOfCourses>0

        BEGIN
            SET @AverageGrade = @TotalMarks/@NumberOfCourses
        END


        CLOSE CalculateAverage
        DEALLOCATE Calculateaverage


         RETURN @AverageGrade



    END;

Answer 1

1. I think you need an initial

   FETCH NEXT FROM CalculateAverage INTO @TotalMarks

between

OPEN CalculateAverage

and

WHILE @@FETCH_STATUS=0

1. What Gordon said. The use of a cursor here is misguided, you can easily do this sort of calc using SQL aggregation. AVG...GROUP BY.

2. I suspect the error is in SET @TotalMarks = @TotalMarks + dbo.CourseEnrollment.FinalGrade as you there really is no reference to dbo.CourseEnrollment available in that line.

Note: I am having some trouble making the formatting stick.

with you declarations:

DECLARE @FinalGrade DECIMAL(5,2)

then OPEN CalculateAverage; FETCH NEXT FROM CalculateAverage INTO @FinalGrade

WHILE @@FETCH_STATUS=0

BEGIN

  SET @NumberOfCourses = @NumberOfCourses + 1
  SET @TotalMarks = @TotalMarks + @FinalGrade   -- @FinalGrade

  FETCH NEXT FROM CalculateAverage INTO @FinalGrade
END

Answer 2

First, a cursor is not needed for this calculation. But, I think your problem is in this line:

    SELECT FinalGrade 
    FROM CourseEnrollment
    WHERE @StudentId=dbo.CourseEnrollment.StudentId

SQL Server has no way of knowing that dbo.CourseEnrollment actually refers to CourseEnrollment. You should get in the habit of using table aliases:

    SELECT FinalGrade 
    FROM CourseEnrollment ce
    WHERE @StudentId = ce.StudentId