在DataGridView中添加一个ComboBox列

我正在使用一个winform datagridview控件来添加，编辑&删除MS Access数据库中的记录。当没有pk-fk关系时，效果很好。现在我想在UserDetails表中添加一个UserTypeId列。UserTypeId来自UserTypes表

Table: UserDetails
--------------------------------------
UserId | UserTypeId | Other fields...|
--------------------------------------
       |            |                |
--------------------------------------
Table: UserTypes
---------------------------
UserTypeId | UserTypeName |
---------------------------
           |              |
---------------------------

这些是我现有的代码-

public partial class frmUser : Form
{
    private String connectionString = null;
    private OleDbConnection connection = null;
    private OleDbDataAdapter da = null;
    private OleDbCommandBuilder commandBuilder = null;
    private DataTable dataTable = null;
    private BindingSource bindingSource = null;
    private String selectQueryString = null;
    public frmUser()
    {
        InitializeComponent();
    }
    private void frmUser_Load(object sender, EventArgs e)
    {
        connectionString = GlobalVariables.ConnectionString;// ConfigurationManager.AppSettings["connectionString"];
        connection = new OleDbConnection(connectionString);
        selectQueryString = "SELECT * FROM UserDetail";
        connection.Open();
        da = new OleDbDataAdapter(selectQueryString, connection);
        commandBuilder = new OleDbCommandBuilder(da);
        dataTable = new DataTable();
        da.Fill(dataTable);
        bindingSource = new BindingSource();
        bindingSource.DataSource = dataTable;
        dataGridViewTrial.DataSource = bindingSource;
        // if you want to hide Identity column
        dataGridViewTrial.Columns[0].Visible = false;
    }
    private void addUpadateButton_Click(object sender, EventArgs e)
    {
        try
        {
            da.Update(dataTable);
        }
        catch (Exception exceptionObj)
        {
            MessageBox.Show(exceptionObj.Message.ToString());
        }
    }
    private void deleteButton_Click(object sender, EventArgs e)
    {
        try
        {
            dataGridViewTrial.Rows.RemoveAt(dataGridViewTrial.CurrentRow.Index);
            da.Update(dataTable);
        }
        catch (Exception exceptionObj)
        {
            MessageBox.Show(exceptionObj.Message.ToString());
        }
    }
}

我怎么能添加一个查找列使用上面的代码?谢谢你。