Question

I have a GradeConversionCriteria table for Student Exam that has three columns:

FromNumber 
ToNumber 
Grade

I want to make a user defined function that will return the Grade when I input marksobtained and totalmarks

If a student gets 45 marks out of 50 I want to return the grade(A,B,C etc.) he achieved.

Answer 1

You want something like this query for your function:

create function ConvertGrades (
    @marksobtained int,
    @totalmarks int
) returns char(1) as
select
    grade
from
    gradeconversioncriteria
where
    @marksobtained/@totalmarks between fromnumber and tonumber

Then you would just do something like this to get the grades:

select
    s.student_id,
    s.student_name,
    t.marksobtained,
    t.totalmarks,
    dbo.ConvertGrades(t.marksobtained, t.totalmarks) as grade_letter
from
    tests t
    inner join students s on
        t.student_id = s.student_id