Open the .sln (solution file) in Visual Studio.
Imports System.Data.SqlClient Public Class frmBilling ' Define global connection string (Adjust to your database setup) Dim connStr As String = "Data Source=.;Initial Catalog=BillingDB;Integrated Security=True" Private Sub btnAddItem_Click(sender As Object, e As EventArgs) Handles btnAddItem.Click ' Validate Inputs If txtProductID.Text = "" OrElse txtQty.Text = "" Then MessageBox.Show("Please select a product and enter quantity.", "Input Error", MessageBoxButtons.OK, MessageBoxIcon.Warning) Exit Sub End If Dim qty As Integer = Convert.ToInt32(txtQty.Text) Dim price As Decimal = Convert.ToDecimal(txtPrice.Text) Dim taxRate As Decimal = Convert.ToDecimal(txtTaxRate.Text) ' Calculate values Dim rawTotal As Decimal = price * qty Dim taxAmount As Decimal = rawTotal * (taxRate / 100) Dim itemGrandTotal As Decimal = rawTotal + taxAmount ' Check if product already exists in the DataGridView For Each row As DataGridViewRow In dgvBillItems.Rows If row.Cells("colProductID").Value IsNot Nothing AndAlso row.Cells("colProductID").Value.ToString() = txtProductID.Text Then ' Update quantity and totals Dim existingQty As Integer = Convert.ToInt32(row.Cells("colQty").Value) row.Cells("colQty").Value = existingQty + qty row.Cells("colTotal").Value = Convert.ToDecimal(row.Cells("colTotal").Value) + itemGrandTotal CalculateBillTotals() ClearItemInputs() Exit Sub End If Next ' Append new item row to DataGridView dgvBillItems.Rows.Add(txtProductID.Text, txtProductName.Text, price, qty, taxRate, itemGrandTotal) CalculateBillTotals() ClearItemInputs() End Sub Private Sub ClearItemInputs() txtProductID.Clear() txtProductName.Clear() txtPrice.Clear() txtTaxRate.Clear() txtQty.Clear() End Sub Use code with caution. Computation Logic: Real-time Aggregate Invoicing
Before writing any VB.NET code, a relational database must be established to handle products, customers, invoices, and transaction logs. Below is the SQL schema designed for SQL Server.
❌ – Many free/cheap source code bundles still use plaintext passwords in connection strings or SQL injection–vulnerable dynamic queries. Always audit before using. vbnet+billing+software+source+code
Public Class LoginForm Private Sub btnLogin_Click(sender As Object, e As EventArgs) Handles btnLogin.Click Dim username As String = txtUsername.Text Dim password As String = txtPassword.Text Dim query As String = $"SELECT Role FROM tbl_Users WHERE Username='username' AND Password='password'" Dim dt As DataTable = ExecuteQuery(query) If dt.Rows.Count > 0 Then Dim role As String = dt.Rows(0)("Role").ToString() Dim mainForm As New MainDashboard(role, username) mainForm.Show() Me.Hide() Else MessageBox.Show("Invalid credentials!") End If End Sub
: Generates summaries of daily sales, stock-in-hand, and profit/loss statements, often using tools like Crystal Reports .
Use Guna UI or Bunifu Framework to give the VB.NET forms a modern, "Flat" look instead of the default grey Windows style. Open the
Remember to always:
: Processes transactions, handles calculations, and generates invoices.
: Protects sensitive financial data through user logins and role-based permissions. 3. Technical Architecture Below is the SQL schema designed for SQL Server
Building your own billing system provides ultimate control over your business workflows, invoicing, and data security. Choosing is a highly reliable path for desktop applications because of its rapid user interface construction and powerful data-binding capabilities.
Billing software is data-heavy. Look for a project that uses (Express or Standard). The code should demonstrate:
What’s typically included: