public string AssignCourse(CourseAssign courseassign) { int assignCourse = courseAssignGateway.AssignCourse(courseassign.TeacherId, courseassign.CourseId); if (assignCourse > 0) { double remainingCredit = courseassign.ReaminingCredit - courseassign.Credit; int updateRemainingCredit = courseAssignGateway.UpdateRemainingCreditOfTeacher(remainingCredit, courseassign.TeacherId); } return("Course Assign Successfully."); }