SqlConnection con567 = new SqlConnection("mydatasourcehere");
SqlCommand xxmd = new SqlCommand("SELECT nome_operador from Operadores", con567);
SqlDataAdapter dat = new SqlDataAdapter();
dat.SelectCommand = xxmd;
DataTable table187 = new DataTable();
dat.Fill(table187);
DataRow itemrow78 = table187.NewRow();
itemrow78[0] = "Selecionar Operador";
table187.Rows.InsertAt(itemrow78, 0);
cmbOperadores.DataSource = table187;
cmbOperadores.DisplayMember = "nome_operador";
SqlConnection con567 = new SqlConnection("mydatasourcehere");
SqlCommand xxmd = new SqlCommand("SELECT nome_operador from Operadores", con567);
SqlDataAdapter dat = new SqlDataAdapter();
dat.SelectCommand = xxmd;
DataTable table187 = new DataTable();
dat.Fill(table187);
DataRow itemrow78 = table187.NewRow();
itemrow78[0] = "Selecionar Operador";
table187.Rows.InsertAt(itemrow78, 0);
cmbOperadores.DataSource = table187;
cmbOperadores.DisplayMember = "nome_operador";