Sql = "insert into Designations values('" + txt_name.Text + "','" + ddldesg.SelectedValue.ToString() + "')";
The above One u wrote derive the values only like
1=principal
2=course officer
3=director Items if Select principal it store one
try this
This following answer is,as per ur database,
Sql = "insert into Designations values('" + txt_name.Text + "','" + ddldesg.SelectedItem.Text + "')";