在订单中保留易失性数据

Question

假设我有表：客户和订单，我想用不可更改的客户信息（如地址、姓名等）存储订单，但不想将所有这些信息复制到订单表中。共有三个选项：

a) Mapping table for base customers
orders
    ....
    customer_id; link to the customers table
    baseCustomer_id; link to the customers_base table
    ....
customers
    id; 
    base_id; link to the base customers table;
    ....
customers_base
    id
    ....

b) Versioning: (if new customer, create version 0 for base customer, and version 1 to have permament record)
orders
    ....
    customer_id
    customer_version
    ....
customers
   id
   version
   ....
c) Create a copy of customer info for each order and store it into the same table; 
orders
   ....
   customer_id
   ....
customers
   id
   ....
   copy_of; refers to the customers.id if null represents base customer entity

所以问题是：从数据库设计、可读性、实现复杂性等不同角度来看，哪种方法更可取？

Answer 1

我推荐类似于@Jeffrey L Whitledge 在database-structure-for-storing-historical-data 中建议的内容

Customer
--------
CustomerId (PK)
Name
AddressId (FK)
PhoneNumber
Email

Order
-----
OrderId (PK)
CustomerId (FK)
ShippingAddressId (FK)
BillingAddressId (FK)
TotalAmount

Address
-------
AddressId (PK)
AddressLine1
AddressLine2
City
Region
Country
PostalCode

etc.

每一个可以改变的数据都要分组，比如地址在这里，如果地址有任何变化，很容易生成一个新的实体，订单行可以继续引用旧的实体。

在数据仓库术语中，这通常称为star schema，您可以在其中区分事实表和维度表。