I Want to control the make EmployeeID in SQL side to be equal to combobox value, so that when I insert update delete, I directly control items by their value. However I get error when I enter this line. Does anyone know why this occurs? 

**NOTE: KennyZ found the solution. Thank you for help, KennyZ.**

```
    void comboboxrefresh()
    {
        cnn.Open();
        SqlCommand cmd = new SqlCommand("SELECT EmployeeID,EmployeeFirstName,EmployeeLastName FROM Employees", cnn);
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.HasRows)
        {
            while (dr.Read())
            {
                comboBox1.Items.Insert(dr.GetString(1) + dr.GetString(2), dr.GetInt32(0));
            }
        }

        cnn.Close();
    }

```