private void button_AssignCourse_Click(object sender, EventArgs e)
 {
     if (comboBox_Teacher.Text != "Select Teacher" && comboBox_Course.Text != "Select Course")
     {
         int courseId  = mysql.getCourseIdByName(comboBox_Course.Text);
         int teacherId = mysql.getTeacherIdByName(comboBox_Teacher.Text);
         mysql.AssignedCourseInsert(courseId, teacherId, comboBox_Course.Text, comboBox_Teacher.Text);
         label_AssinCourseMessage.ForeColor = Color.Green;
         label_AssinCourseMessage.Text      = "Course Added Successfully";
         label_AssinCourseMessage.Show();
     }
     else
     {
         label_AssinCourseMessage.ForeColor = Color.Red;
         label_AssinCourseMessage.Text      = "Kindly, fill all the fields.";
         label_AssinCourseMessage.Show();
     }
 }