データベーススキーマには何をお勧めしますか？名前、住所、連絡先などの顧客情報を保存し、どの請求書が支払われ、どの請求書が遅れているかを追跡したいと思います。
What would you recommend for the database schema?   I want to store customer information such as their name, address and contact details and track which invoices have been paid and which are overdue.