Private Sub btnAddItem_Click(sender As Object, e As EventArgs) Handles btnAddItem.Click ' Assume txtProductCode, txtQuantity, dgvCart are controls Dim productCode As String = txtProductCode.Text.Trim Dim qty As Integer = Integer.Parse(txtQuantity.Text) ' Fetch product from DB Dim cmd As New SqlCommand("SELECT ProductID, ProductName, UnitPrice, GST_Percent, StockQuantity FROM tbl_Product WHERE ProductCode=@code", con) cmd.Parameters.AddWithValue("@code", productCode) Dim da As New SqlDataAdapter(cmd) Dim dt As New DataTable da.Fill(dt)
Private Sub UpdateGrandTotal() Dim grandTotal As Decimal = 0 For Each row As DataRow In dtCart.Rows grandTotal += CDec(row("Total")) Next lblGrandTotal.Text = "Grand Total: ₹" & grandTotal.ToString("N2") End Sub vb.net billing software source code
-- Product Master CREATE TABLE tbl_Product ( ProductID INT PRIMARY KEY IDENTITY(1,1), ProductCode NVARCHAR(50) UNIQUE, ProductName NVARCHAR(200), UnitPrice DECIMAL(18,2), GST_Percent DECIMAL(5,2), -- 5, 12, 18, 28 StockQuantity INT DEFAULT 0, ReorderLevel INT DEFAULT 5 ); Private Sub btnAddItem_Click(sender As Object
Try DBConnection.OpenConnection() Dim transaction As SqlTransaction = DBConnection.conn.BeginTransaction() StockQuantity FROM tbl_Product WHERE ProductCode=@code"
: Use TextBox for manual entry and NumericUpDown for item quantities.
"The lack of a layered architecture makes the application brittle. For example, if the database schema changes, modifications are required directly in the UI event handlers (e.g., BtnSave_Click ), violating the Open/Closed Principle."
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