Your first example is actually a mutant hybrid of camel-cased underscores. Observe: if(accounts_orders_invoices_table.order_onvoice_number == order_invoice_

Your first example is actually a mutant hybrid of camel-cased underscores. Observe: if(accounts_orders_invoices_table.order_onvoice_number == order_invoice_number){ ...} Versus yours: if(Accounts_Orders_Invoices_Table.Order_Invoice_Number == Order_Invoice_Number){ ...} I would be, perhaps, moderately ticked off to have to have to deal with code that looked like that, and used both, in a real world scenario.