Load the second combobox

Question

Hi!

I have a combobox with three items:
Toyota
Kia
Hyndai

Then I have a small table with two columns (Marks and Models):

Marks  | Modelos
Toyota: Camry
Toyota: Celica
Toyota: Corolla
Kia: Optima
Kia: Picanto
Kia: Sportage
Hyundai: Accent
Hyundai: Azera
Hyundai: Elantra

When I select one mark. What happening? I found in the combobox model the table's name repeted in that combobox:

string connectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\rentacar\rentacar\\app_data\rentacar.mdb;Persist Security Info=False";

            OleDbConnection sqlCon = new OleDbConnection(connectionString);

            sqlCon.Open();

            string commandString = "select * from carsconfig where cars ='" + cbxMarkConfig.Text + "'";

            OleDbCommand sqlCmd = new OleDbCommand(commandString, sqlCon);

            OleDbDataReader read = sqlCmd.ExecuteReader();

            if (read.HasRows)

            {

                while (read.Read())

                {

                    cbxModelsConfig.Items.Add("models"); // it will show the code

                    

                }

            }

            else

            {

                MessageBox.Show("A record with a code of " + cbxMarkConfig.Text + " was not found");

            }

        }

    }