Vbnet+billing+software+source+code May 2026

Imports System.Data.SqlClient
Public Class frmInvoice
Private dtDetails As New DataTable()
Private Sub frmInvoice_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    txtInvoiceDate.Text = DateTime.Now.ToString("yyyy-MM-dd")
    LoadInvoiceNumber()
    LoadCustomers()
    InitializeDetailsGrid()
End Sub
Private Sub LoadInvoiceNumber()
    Dim query As String = "SELECT ISNULL(MAX(CAST(SUBSTRING(InvoiceNo, 3, LEN(InvoiceNo)) AS INT)), 0) + 1 FROM tbl_Invoice_Master WHERE InvoiceNo LIKE 'IN%'"
    Dim nextNum As Integer = Convert.ToInt32(ExecuteScalar(query))
    txtInvoiceNo.Text = "IN" & nextNum.ToString("D6")
End Sub
Private Sub LoadCustomers()
    Dim dt As DataTable = GetDataTable("SELECT CustomerID, CustomerName FROM tbl_Customers")
    cmbCustomer.DisplayMember = "CustomerName"
    cmbCustomer.ValueMember = "CustomerID"
    cmbCustomer.DataSource = dt
End Sub
Private Sub InitializeDetailsGrid()
    dtDetails.Columns.Add("ProductID", GetType(Integer))
    dtDetails.Columns.Add("ProductName", GetType(String))
    dtDetails.Columns.Add("Quantity", GetType(Decimal))
    dtDetails.Columns.Add("Rate", GetType(Decimal))
    dtDetails.Columns.Add("TaxableValue", GetType(Decimal))
    dtDetails.Columns.Add("CGST", GetType(Decimal))
    dtDetails.Columns.Add("SGST", GetType(Decimal))
    dgvDetails.DataSource = dtDetails
End Sub
Private Sub btnAddProduct_Click(sender As Object, e As EventArgs) Handles btnAddProduct.Click
    ' Assume a popup product search form returns selected product
    Dim frm As New frmProductSearch()
    If frm.ShowDialog() = DialogResult.OK Then
        Dim newRow As DataRow = dtDetails.NewRow()
        newRow("ProductID") = frm.SelectedProductID
        newRow("ProductName") = frm.SelectedProductName
        newRow("Quantity") = 1
        newRow("Rate") = frm.Rate
        ' Tax calculation will be done row-by-row based on GST%
        Dim gstPercent As Decimal = frm.GSTPercent
        Dim taxable As Decimal = newRow("Quantity") * newRow("Rate")
        newRow("TaxableValue") = taxable
        newRow("CGST") = Math.Round(taxable * (gstPercent / 100) / 2, 2)
        newRow("SGST") = Math.Round(taxable * (gstPercent / 100) / 2, 2)
        dtDetails.Rows.Add(newRow)
        CalculateTotals()
    End If
End Sub
Private Sub CalculateTotals()
    Dim subTotal As Decimal = 0
    Dim totalCGST As Decimal = 0
    Dim totalSGST As Decimal = 0
For Each row As DataRow In dtDetails.Rows
        subTotal += CDec(row("TaxableValue"))
        totalCGST += CDec(row("CGST"))
        totalSGST += CDec(row("SGST"))
    Next
lblSubtotal.Text = subTotal.ToString("N2")
    lblTotalCGST.Text = totalCGST.ToString("N2")
    lblTotalSGST.Text = totalSGST.ToString("N2")
    lblGrandTotal.Text = (subTotal + totalCGST + totalSGST).ToString("N2")
End Sub
Private Sub btnSaveInvoice_Click(sender As Object, e As EventArgs) Handles btnSaveInvoice.Click
    If dtDetails.Rows.Count = 0 Then
        MessageBox.Show("Add at least one product")
        Return
    End If
Using conn As New SqlConnection(ConnectionString)
        conn.Open()
        Dim transaction = conn.BeginTransaction()
Try
            ' Insert into Invoice Master
            Dim masterCmd As New SqlCommand("INSERT INTO tbl_Invoice_Master (InvoiceNo, InvoiceDate, CustomerID, SubTotal, TotalCGST, TotalSGST, GrandTotal) VALUES (@invNo, @date, @custId, @sub, @cgst, @sgst, @grand)", conn, transaction)
            masterCmd.Parameters.AddWithValue("@invNo", txtInvoiceNo.Text)
            masterCmd.Parameters.AddWithValue("@date", Convert.ToDateTime(txtInvoiceDate.Text))
            masterCmd.Parameters.AddWithValue("@custId", cmbCustomer.SelectedValue)
            masterCmd.Parameters.AddWithValue("@sub", CDec(lblSubtotal.Text))
            masterCmd.Parameters.AddWithValue("@cgst", CDec(lblTotalCGST.Text))
            masterCmd.Parameters.AddWithValue("@sgst", CDec(lblTotalSGST.Text))
            masterCmd.Parameters.AddWithValue("@grand", CDec(lblGrandTotal.Text))
            masterCmd.ExecuteNonQuery()
' Insert Details
            For Each row As DataRow In dtDetails.Rows
                Dim detailCmd As New SqlCommand("INSERT INTO tbl_Invoice_Details (InvoiceNo, ProductID, Quantity, Rate, TaxableValue, CGST_Amount, SGST_Amount) VALUES (@invNo, @pid, @qty, @rate, @taxable, @cgst, @sgst)", conn, transaction)
                detailCmd.Parameters.AddWithValue("@invNo", txtInvoiceNo.Text)
                detailCmd.Parameters.AddWithValue("@pid", row("ProductID"))
                detailCmd.Parameters.AddWithValue("@qty", row("Quantity"))
                detailCmd.Parameters.AddWithValue("@rate", row("Rate"))
                detailCmd.Parameters.AddWithValue("@taxable", row("TaxableValue"))
                detailCmd.Parameters.AddWithValue("@cgst", row("CGST"))
                detailCmd.Parameters.AddWithValue("@sgst", row("SGST"))
                detailCmd.ExecuteNonQuery()
            Next
transaction.Commit()
            MessageBox.Show("Invoice Saved Successfully!")
            Me.Close()
        Catch ex As Exception
            transaction.Rollback()
            MessageBox.Show("Error: " & ex.Message)
        End Try
    End Using
End Sub

End Class

Create a database named BillingDB and run the following scripts:

CREATE TABLE tbl_InvoiceDetails (
    ID INT PRIMARY KEY IDENTITY,
    InvoiceNo NVARCHAR(20) FOREIGN KEY REFERENCES tbl_Invoices(InvoiceNo),
    ProductID INT FOREIGN KEY REFERENCES tbl_Products(ProductID),
    Quantity INT,
    Price DECIMAL(18,2),
    GST_Amount DECIMAL(18,2),
    Total DECIMAL(18,2)
);

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Add a PrintDocument control and its PrintPage event. vbnet+billing+software+source+code

Private WithEvents pd As New Printing.PrintDocument
Private invoiceContent As String
Private Sub PrintInvoice(ByVal invNo As String)
' Build invoice text
Dim sb As New System.Text.StringBuilder()
sb.AppendLine("   MY BILLING SOFTWARE   ")
sb.AppendLine("--------------------------")
sb.AppendLine($"Invoice No: invNo")
sb.AppendLine($"Date: DateTime.Now")
sb.AppendLine("--------------------------")
sb.AppendLine("Item     Qty  Price  Total")
For Each row As DataRow In cartTable.Rows
sb.AppendLine($"row("ProductName")  row("Quantity")  row("Price")  row("Total")")
Next
sb.AppendLine("--------------------------")
sb.AppendLine($"Grand Total: lblGrandTotal.Text")
sb.AppendLine("--------------------------")
sb.AppendLine("      Thank you!           ")
invoiceContent = sb.ToString()
pd.Print()

End Sub
Private Sub pd_PrintPage(sender As Object, e As Printing.PrintPageEventArgs) Handles pd.PrintPage
Dim font As New Font("Courier New", 10)
Dim yPos As Single = 10
Dim leftMargin As Single = e.MarginBounds.Left
Dim lines As String() = invoiceContent.Split(Environment.NewLine)
For Each line As String In lines
    e.Graphics.DrawString(line, font, Brushes.Black, leftMargin, yPos)
    yPos += font.GetHeight(e.Graphics)
Next

End Sub

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