SqlCommand mycommand = new SqlCommand("select id, name from tablename", myCon);
SqlDataReader dr = mycommand.ExecuteReader();
while (dr.Read())
{
id_cmb.Items.Add(dr.GetValue(0));
name_cmb.Items.Add(dr.GetValue(1));
}
Your Above SQL Query not satisfying your condition whatever you want......
If you want to display distinct value in combobox then you will not able to find unique ID for that records (if u have same name with different ID).........So either change your database table with unique Name and ID or don't select ID
select distinct name from tablename