You loose some features of SQL when you have historical values.
For example if you only want customers to create orders you can set a foreign key between customer and order. If you don't delete orders and customers, then the database will allow you to insert new orders against old customers, unless you apply a more complex constraint.
For example if you only want customers to create orders you can set a foreign key between customer and order. If you don't delete orders and customers, then the database will allow you to insert new orders against old customers, unless you apply a more complex constraint.