你需要在MySQL中设置外键吗？(Do you need to set foreign keys in MySQL?)

 假设你在MySQL数据库中有两个如下所示的表： 
 
 TABLE人物： 
 
  primary key: PERSON_ID,
  NAME,
  SURNAME, etc.
 
 TABLE地址： 
 
  primary key: ADDRESS_ID,
  foreign key: PERSON_ID,
  addressLine1, etc.
 
 如果您管理行的创建（在这两个表中）以及通过PHP检索数据，您是否还需要在数据库中创建物理关系？ 如果是，为什么？ 

Let's say you have got two tables like the following in a MySQL database:
 
TABLE people:
 
  primary key: PERSON_ID,
  NAME,
  SURNAME, etc.
 
TABLE addresses:
 
  primary key: ADDRESS_ID,
  foreign key: PERSON_ID,
  addressLine1, etc.
 
If you manage the creation of rows (in both table) and the retrieving of data trough PHP do you still need to create a physical relationship in the database? If yes, why?

原文：https://stackoverflow.com/questions/13086160