Vbnet+billing+software+source+code [patched] ✅

VB.NET billing software source code is a popular choice for students and small business developers looking for a cost-effective way to build desktop-based accounting solutions. Because VB.NET uses simple, readable syntax, it is highly accessible for beginners. Core Features of VB.NET Billing Systems

1. Presentation Layer (UI): Developed using Windows Forms (WinForms). Provides the graphical interface for user interaction (Data entry, Grid views).
2. Business Logic Layer (BLL): Contains VB.NET classes that enforce business rules (e.g., calculating totals, checking stock levels before sale).
3. Data Access Layer (DAL): Handles connectivity with the database using ADO.NET. This layer executes SQL queries for CRUD (Create, Read, Update, Delete) operations.

Public Class frmSearchInvoice
    Private Sub btnSearch_Click(sender As Object, e As EventArgs) Handles btnSearch.Click
        Dim query As String = "SELECT InvoiceNo, InvoiceDate, CustomerName, GrandTotal FROM tbl_Invoice_Master m INNER JOIN tbl_Customers c ON m.CustomerID = c.CustomerID WHERE InvoiceNo LIKE '%' + @search + '%'"
        Dim param As SqlParameter = New SqlParameter("@search", txtSearch.Text)
        dgvInvoices.DataSource = GetDataTable(query, param)
    End Sub
Private Sub dgvInvoices_DoubleClick(sender As Object, e As EventArgs) Handles dgvInvoices.DoubleClick
    Dim selectedInvoice As String = dgvInvoices.CurrentRow.Cells("InvoiceNo").Value.ToString()
    Dim frm As New frmInvoice()
    frm.LoadInvoiceForEdit(selectedInvoice)   ' Implement this method to fetch existing invoice
    frm.ShowDialog()
End Sub

' Example: Calculating total on DataGridView Cell End Edit
Private Sub dgvCart_CellEndEdit(sender As Object, e As DataGridViewCellEventArgs) Handles dgvCart.CellEndEdit
    If e.ColumnIndex = dgvCart.Columns("Quantity").Index Then
        Dim qty As Integer = CInt(dgvCart.Rows(e.RowIndex).Cells("Quantity").Value)
        Dim price As Decimal = CDec(dgvCart.Rows(e.RowIndex).Cells("Price").Value)
Private Sub txtProductCode_KeyDown(sender As Object, e As KeyEventArgs) Handles txtProductCode.KeyDown
    If e.KeyCode = Keys.Enter Then
        Dim productCode As String = txtProductCode.Text.Trim()
        Dim query As String = $"SELECT ProductID, ProductName, UnitPrice, StockQuantity, GST_Percent FROM tbl_Products WHERE ProductCode='productCode'"
        Dim dt As DataTable = ExecuteQuery(query)
ER Diagram Concept:
tbl_Customers (1) ----< (N) tbl_Invoices (1) ----< (N) tbl_InvoiceItems >---- (1) tbl_Products vbnet+billing+software+source+code