//delete instructor to choosen course
private void button6_Click(object sender, EventArgs e)
{
try
{
int crsId = int.Parse(comboBox1.Text);
using (Online_Exame ent = new Online_Exame())
{
//--get instractor from combo box
string insName = Instructors.SelectedItem.ToString();
var insId = (int)(ent.Get_insid_by_inname(insName)).First();
ent.Delete_course_instractor(crsId, insId);
MessageBox.Show("Deleted Successfully");
Courses.Items.Clear();
Instructors.Items.Clear();
label7.Text = comboBox1.Text = comboBox3.Text = textBox1.Text = string.Empty;
ent.SaveChanges();
}
}
catch (System.Data.Entity.Core.EntityCommandExecutionException)
{
MessageBox.Show("This instructor already exist");
}
catch (InvalidOperationException)
{
MessageBox.Show("Please Choose Instructor Name");
}
catch (NullReferenceException)
{
MessageBox.Show("Please Choose Instructor Name");
}
catch (System.FormatException)
{
MessageBox.Show("Please Choose Course ID");
}
}