private void btInsert_Click(object sender, EventArgs e)
 {
     if (tbCustomerCompany.TextLength == 0)
     {
         MessageBox.Show("客户名称不能为空!");
         return;
     }
     if (db.InsertCustomer(tbCustomerCompany.Text, tbCustomerName.Text, tbPhoneNumber.Text, tbAddress.Text) != 0)
     {
         if (fcs == null)
         {
             f.FormCustomerManager_Load(sender, e);
         }
         else
         {
             fcs.FormCustomerSearch_Load(sender, e);
         }
         this.Close();
         return;
     }
     MessageBox.Show("添加失败!");
 }