//---- delete courses
private void button3_Click(object sender, EventArgs e)
{
try
{
int crsid = (int)comboBox1.SelectedItem;
using (Online_Exame ent = new Online_Exame())
{
ent.deleteCourse(crsid);
ent.SaveChanges();
}
MessageBox.Show("Deleted Successfully");
Courses.Items.Clear();
Instructors.Items.Clear();
label7.Text = comboBox1.Text = comboBox3.Text = textBox1.Text = string.Empty;
LoadCourses();
}
catch (NullReferenceException)
{
MessageBox.Show("Incorrect ID");
}
}