For more advanced, object-oriented implementations, you can explore these specialized tutorials and repositories:
Module DatabaseHelper ' Change this connection string to match your SQL Server instance Public ConnectionString As String = "Data Source=localhost;Initial Catalog=BillingDB;Integrated Security=True"
' Calculate Line Total dgvCart.Rows(e.RowIndex).Cells("LineTotal").Value = qty * price
' 1. Insert Invoice Header Using cmd As New SqlCommand(queryInvoice, conn, transaction) cmd.Parameters.AddWithValue("@Date", DateTime.Now) cmd.Parameters.AddWithValue("@CID", customerId) cmd.Parameters.AddWithValue("@Total", totalAmount) invoiceId = Convert.ToInt32(cmd.ExecuteScalar()) End Using vbnet+billing+software+source+code