Auto-Complete in textbox using data from a SQL Server database

I am trying to get my textbox to auto-complete when a user types in it to write a query. This would be similar to how SQL Server Management Studio does it and gives the option as you type to arrow down or click on a table name or column name. Here is the following code I have.

public void loadData()
{
    var myConnection = new SqlConnection(DBConnectionBox.Text);
    myConnection.Open();

    AutoCompleteStringCollection namesCollection = new AutoCompleteStringCollection();
    string query = @"Select distinct [name] from [INFORMATION_SCHEMA.TABLES]";

    SqlCommand cmd = new SqlCommand(query, myConnection);

    SqlDataReader dr = cmd.ExecuteReader();

    if (dr.HasRows == true)
    {
        while (dr.Read())
            namesCollection.Add(dr["name"].ToString());
    }

    dr.Close();
    myConnection.Close();

    ManualQueryBox.AutoCompleteMode = AutoCompleteMode.Append;
    ManualQueryBox.AutoCompleteSource = AutoCompleteSource.CustomSource;
    ManualQueryBox.AutoCompleteCustomSource = namesCollection;
}

private void ManualQueryBox_KeyUp(object sender, KeyEventArgs e)
{
    loadData();
}

This is the code I use to grab what is in the textbox and execute it.

private void ExecuteBtn_Click(object sender, EventArgs e)
{
    this.ClientInfoDGV.DataSource = null;
    this.ClientInfoDGV.Rows.Clear();

    var myConnection = new SqlConnection(DBConnectionBox.Text);

    var ManualCmd = new SqlCommand(ManualQueryBox.Text);
    ManualCmd.Connection = myConnection;
    ManualCmd.CommandType = CommandType.Text;

    SqlDataAdapter SqlAdap = new SqlDataAdapter(ManualCmd);
    DataTable MQRecord = new DataTable();
    SqlAdap.Fill(MQRecord);

    ClientInfoDGV.DataSource = MQRecord;
}

I have never done autofill before but looking around I have see some asp.net AJAX control toolkit, but I am not entirely sure how that all works. Any help is welcome.

Update to auto-fill code

public void loadData()
        {
            var myConnection = new SqlConnection(DBConnectionBox.Text);
            myConnection.Open();
            AutoCompleteStringCollection namesCollection = new AutoCompleteStringCollection();
            string query = @"Select distinct [Id] from [Clients]";
            SqlCommand cmd = new SqlCommand(query, myConnection);
            SqlDataReader dr = cmd.ExecuteReader();
            if (dr.HasRows == true)
            {
                while (dr.Read())
                    namesCollection.Add(dr["id"].ToString());

            }

            dr.Close();
            myConnection.Close();

            ManualQueryBox.AutoCompleteMode = AutoCompleteMode.SuggestAppend;
            ManualQueryBox.AutoCompleteSource = AutoCompleteSource.CustomSource;
            ManualQueryBox.AutoCompleteCustomSource = namesCollection;
        }