Vbnet+billing+software+source+code May 2026

' Check if already in cart Dim existingRow() As DataRow = cartTable.Select($"ProductID = productID") If existingRow.Length > 0 Then existingRow(0)("Quantity") += 1 Dim qty As Integer = Convert.ToInt32(existingRow(0)("Quantity")) Dim totalBeforeGST As Decimal = qty * price Dim gstAmt As Decimal = totalBeforeGST * (gstPercent / 100) existingRow(0)("GST_Amount") = gstAmt existingRow(0)("Total") = totalBeforeGST + gstAmt Else Dim gstAmt As Decimal = price * (gstPercent / 100) Dim totalWithGST As Decimal = price + gstAmt cartTable.Rows.Add(productID, pName, 1, price, gstPercent, gstAmt, totalWithGST) End If CalculateTotals() txtProductCode.Clear() txtProductCode.Focus() Else MessageBox.Show("Product not found!") End If End If End Sub

Dim invoiceNo As String = "INV-" & DateTime.Now.ToString("yyyyMMddHHmmss") Dim customerID As Integer = GetOrCreateCustomer(txtCustomerMobile.Text) ' Function to fetch/add customer Dim userId As Integer = CurrentUserID ' Assume global login user ID vbnet+billing+software+source+code

' Insert into tbl_Invoices Dim insertInvoice As String = $"INSERT INTO tbl_Invoices (InvoiceNo, CustomerID, SubTotal, GST_Amount, GrandTotal, UserID) VALUES ('invoiceNo', customerID, lblSubTotal.Text, lblGST.Text, lblGrandTotal.Text, userId)" ExecuteNonQuery(insertInvoice) ' Check if already in cart Dim existingRow()