private void SalesManagerForm_Load(object sender, EventArgs e)
{
textBoxCustomerID.Enabled = false; // Disable CustomerID textBox
comboBoxSearch.Items.Add("CustomerID");
comboBoxSearch.Items.Add("CustomerName");
comboBoxSearch.Items.Add("City");
comboBoxSearch.Items.Add("PostalCode");
comboBoxSearch.Items.Add("PhoneNumber");
comboBoxSearch.Items.Add("FaxNumber");
comboBoxSearch.Text = comboBoxSearch.Items[0] as string;
SalesManager salesManager = new SalesManager();
this.dsProject = salesManager.CreateDataSetTable(this.dsProject, this.dtCustomer);
salesManager.ReadData(this.dsProject, this.dtCustomer);
dataGridViewDisplay.DataSource = dtCustomer;
}