/// <summary>
/// This method requires a user id in order to get all the grades of that user.
/// </summary>
/// <param name="id">The id</param>
/// <returns>Returns a list of all grades of the selected user.</returns>
public List <PrestationIndicator> getAverageGradeById(int id)
{
QueryStrings queryStrings = new QueryStrings();
List <PrestationIndicator> gradeList = queryStrings.getAverageGradeById(id);
return(gradeList);
}