Vb.net Billing Software Source Code _best_ Jun 2026

--- ## 5. Critical Engineering Principles Applied ### Acid-Compliant Transactions The saving mechanism utilizes `SqlTransaction`. This guarantees that if any operation fails midway—such as an out-of-stock database restriction or network failure during row insertion—the entire database transaction rolls back. This prevents orphaned records where a customer is charged but the items fail to register. ### Automated Inventory Deduction When line items are finalized, the system updates the inventory levels inside the `Products` table using atomic SQL operations (`StockQuantity = StockQuantity - @Qty`). This prevents synchronization issues across concurrent point-of-sale stations. ### Input Sanitization and Parametric Queries The source code completely eliminates SQL injection vulnerabilities by abandoning string concatenation in favor of strict typed mapping using `SqlCommand.Parameters.AddWithValue`. --- ## 6. Expanding the System To scale this foundational template up to an enterprise-grade product, consider integrating these advanced features: * **Reporting Module**: Add Crystal Reports or Microsoft Report Viewer (RDLC) to output physical, printable PDFs. * **Barcode Scanner Integration**: Program the text entry systems to instantly match raw string inputs from commercial USB or Bluetooth barcode scanning hardware. * **Asynchronous Database Calls**: Update standard `ExecuteNonQuery` calls to `ExecuteNonQueryAsync` to keep the UI completely responsive during heavy enterprise transactions. If you would like to expand this system further, Share public link

If product.AddProduct() Then MessageBox.Show("Product added successfully!") ClearFields() LoadProducts() End If End If End Sub

When the "Finish" button is clicked, the software must loop through the grid and save each line item to the InvoiceItems table while updating the Products table to reduce stock. 5. Why VB.NET for Billing? vb.net billing software source code

: Secures the system by requiring a username and password before access is granted. Product Management --- ## 5

Imports System.Data.OleDb Public Class frmBilling ' Global variables for calculations Dim taxRate As Double = 0.18 ' 18% Tax Example Dim invoiceSubTotal As Double = 0.0 Private Sub frmBilling_Load(sender As Object, e As EventArgs) Handles MyBase.Load InitializeCartGrid() ClearForm() End Sub ' Initialize DataGridView columns programmatically Private Sub InitializeCartGrid() dgvCart.Columns.Clear() dgvCart.Columns.Add("id", "Product ID") dgvCart.Columns.Add("code", "Code") dgvCart.Columns.Add("name", "Product Name") dgvCart.Columns.Add("price", "Price") dgvCart.Columns.Add("qty", "Qty") dgvCart.Columns.Add("total", "Total") dgvCart.AllowUserToAddRows = False End Sub ' Auto-fetch product details when a barcode or code is entered Private Sub txtProductCode_KeyDown(sender As Object, e As KeyEventArgs) Handles txtProductCode.KeyDown If e.KeyCode = Keys.Enter AndAlso txtProductCode.Text.Trim() <> "" Then Try OpenConnection() Dim cmd As New OleDbCommand("SELECT ProductID, ProductName, Price FROM Products WHERE ProductCode = ?", conn) cmd.Parameters.AddWithValue("?", txtProductCode.Text.Trim()) Dim dr As OleDbDataReader = cmd.ExecuteReader() If dr.Read() Then txtProductID.Text = dr("ProductID").ToString() txtProductName.Text = dr("ProductName").ToString() txtPrice.Text = dr("Price").ToString() txtQty.Text = "1" txtQty.Focus() Else MessageBox.Show("Product not found!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning) txtProductCode.Clear() End If dr.Close() Catch ex As Exception MessageBox.Show(ex.Message) Finally CloseConnection() End Try End If End Sub ' Add Selected Item to the DataGridView Cart Private Sub btnAddToCart_Click(sender As Object, e As EventArgs) Handles btnAddToCart.Click If txtProductID.Text = "" OrElse Val(txtQty.Text) <= 0 Then MessageBox.Show("Please select a valid product and enter quantity.", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Exclamation) Exit Sub End If Dim itemId As String = txtProductID.Text Dim price As Double = Convert.ToDouble(txtPrice.Text) Dim qty As Integer = Convert.ToInt32(txtQty.Text) Dim itemTotal As Double = price * qty ' Check if product already exists in the cart grid Dim itemExists As Boolean = False For Each row As DataGridViewRow In dgvCart.Rows If row.Cells("id").Value.ToString() = itemId Then Dim currentQty As Integer = Convert.ToInt32(row.Cells("qty").Value) Dim newQty As Integer = currentQty + qty row.Cells("qty").Value = newQty row.Cells("total").Value = (price * newQty).ToString("F2") itemExists = True Exit For End If Next ' If item is new, add it as a new row If Not itemExists Then dgvCart.Rows.Add(itemId, txtProductCode.Text, txtProductName.Text, price.ToString("F2"), qty, itemTotal.ToString("F2")) End If CalculateInvoiceTotals() ClearProductInputs() txtProductCode.Focus() End Sub ' Calculate Subtotal, Tax, and Grand Total Private Sub CalculateInvoiceTotals() invoiceSubTotal = 0.0 For Each row As DataGridViewRow In dgvCart.Rows invoiceSubTotal += Convert.ToDouble(row.Cells("total").Value) Next Dim taxAmount As Double = invoiceSubTotal * taxRate Dim grandTotal As Double = invoiceSubTotal + taxAmount lblSubTotal.Text = invoiceSubTotal.ToString("F2") lblTax.Text = taxAmount.ToString("F2") lblGrandTotal.Text = grandTotal.ToString("F2") End Sub ' Save Bill Details to Database and Update Inventory Stocks Private Sub btnSavePrint_Click(sender As Object, e As EventArgs) Handles btnSavePrint.Click If dgvCart.Rows.Count = 0 Then MessageBox.Show("Cart is empty!", "Error", MessageBoxButtons.OK, MessageBoxIcon.Warning) Exit Sub End If Try OpenConnection() ' 1. Insert Customer Record (Or lookup existing ID) Dim cmdCust As New OleDbCommand("INSERT INTO Customers (CustomerName, ContactNumber) VALUES (?, ?)", conn) cmdCust.Parameters.AddWithValue("?", If(txtCustName.Text = "", "Walking Customer", txtCustName.Text.Trim())) cmdCust.Parameters.AddWithValue("?", txtCustContact.Text.Trim()) cmdCust.ExecuteNonQuery() ' Fetch last generated Customer ID Dim cmdGetCustID As New OleDbCommand("SELECT @@IDENTITY", conn) Dim customerId As Integer = Convert.ToInt32(cmdGetCustID.ExecuteScalar()) ' 2. Insert Parent Invoice Record Dim cmdInv As New OleDbCommand("INSERT INTO Invoices (InvoiceDate, CustomerID, SubTotal, TaxAmount, GrandTotal, PaymentMode) VALUES (?, ?, ?, ?, ?, ?)", conn) cmdInv.Parameters.AddWithValue("?", DateTime.Now) cmdInv.Parameters.AddWithValue("?", customerId) cmdInv.Parameters.AddWithValue("?", Convert.ToDouble(lblSubTotal.Text)) cmdInv.Parameters.AddWithValue("?", Convert.ToDouble(lblTax.Text)) cmdInv.Parameters.AddWithValue("?", Convert.ToDouble(lblGrandTotal.Text)) cmdInv.Parameters.AddWithValue("?", cbPaymentMode.SelectedItem.ToString()) cmdInv.ExecuteNonQuery() ' Fetch last generated Invoice Number Dim cmdGetInvNo As New OleDbCommand("SELECT @@IDENTITY", conn) Dim newInvoiceNo As Integer = Convert.ToInt32(cmdGetInvNo.ExecuteScalar()) ' 3. Insert Line Items into Details Table & Update Inventory Stocks For Each row As DataGridViewRow In dgvCart.Rows Dim pId As Integer = Convert.ToInt32(row.Cells("id").Value) Dim qty As Integer = Convert.ToInt32(row.Cells("qty").Value) Dim price As Double = Convert.ToDouble(row.Cells("price").Value) Dim total As Double = Convert.ToDouble(row.Cells("total").Value) ' Insert details Dim cmdDetails As New OleDbCommand("INSERT INTO InvoiceDetails (InvoiceNo, ProductID, Qty, UnitPrice, Total) VALUES (?, ?, ?, ?, ?)", conn) cmdDetails.Parameters.AddWithValue("?", newInvoiceNo) cmdDetails.Parameters.AddWithValue("?", pId) cmdDetails.Parameters.AddWithValue("?", qty) cmdDetails.Parameters.AddWithValue("?", price) cmdDetails.Parameters.AddWithValue("?", total) cmdDetails.ExecuteNonQuery() ' Deduct from Product Inventory Stock Dim cmdStock As New OleDbCommand("UPDATE Products SET Stocks = Stocks - ? WHERE ProductID = ?", conn) cmdStock.Parameters.AddWithValue("?", qty) cmdStock.Parameters.AddWithValue("?", pId) cmdStock.ExecuteNonQuery() Next MessageBox.Show("Transaction saved successfully! Invoice No: " & newInvoiceNo, "Success", MessageBoxButtons.OK, MessageBoxIcon.Information) ClearForm() Catch ex As Exception MessageBox.Show("Error occurred while saving transaction: " & ex.Message, "Database Error", MessageBoxButtons.OK, MessageBoxIcon.Error) Finally CloseConnection() End Try End Sub ' Reset Helper Procedures Private Sub ClearProductInputs() txtProductID.Clear() txtProductCode.Clear() txtProductName.Clear() txtPrice.Clear() txtQty.Clear() End Sub Private Sub ClearForm() ClearProductInputs() txtCustName.Clear() txtCustContact.Clear() dgvCart.Rows.Clear() lblSubTotal.Text = "0.00" lblTax.Text = "0.00" lblGrandTotal.Text = "0.00" cbPaymentMode.SelectedIndex = 0 End Sub End Class Use code with caution. 4. Scalable Features to Implement Next

: Bind the txtProductID.TextChanged or KeyPress events to match barcode lookup sequences, removing manual typing dependencies. This prevents orphaned records where a customer is

If you are searching for "," you are likely looking to do one of three things: build a custom solution for your business, learn how billing logic works under the hood, or modify an open-source project to fit specific needs.

Create the database abstraction layers to handle data connectivity cleanly.