public Double CalculateGPA(int studentId)
{
var commandForSum = String.Format("SELECT SUM(Total) FROM StudentCourses where StudentId = {0}", studentId);
var commandForCountOfSubjects = String.Format("SELECT count(*) FROM StudentCourses where StudentId = {0} GROUP by StudentId", studentId);
var sum = _dbaccess.SumOfTotal(commandForSum, connectionString);
var countOfSubjects = _dbaccess.CountOfSubjects(commandForCountOfSubjects, connectionString);
var total = sum / countOfSubjects;
Double GPA = (total - 50) / 10;
if (GPA < 0)
{
GPA = 0;
}
else if (GPA > 5)
{
GPA = 5;
}
var GPACommand = String.Format("Update Student set GPA = {0} where StudentId = {1}", GPA, studentId);
_dbaccess.UpdateGPA(GPACommand, connectionString);
return(GPA);
}