how to decrease stock when we sold an item in IMS

Here i am going to show you that how to how to decrease stock when we sold an item in Inventory Management System here we need to decrease stock quantity when we sold an item and moreover you can use this system in multiple environment like how to developed Stock management system in c#,how to developed Sales And Inventory System C#, C# tutorial for build inventory management system, how to developed supermarket management software, how to developed medical store management system