PHP类应该如何与MySQL数据库交互？

The other day, while developing my PHP project and implementing the User class, i started to wonder how this class should interact with the MySQL database the project is using.

Let me start with an example: let's say I have a getName() method, inside the User class, that returns the user's real name. What's the more fitting way to implement that method?

I came up with 2 solutions:

1. I put the DB query inside the getName() and only get what I need like this:

   public function getName() {
   
       // MySQL query code here
   }
   

2. I create a load() method inside the User class that load all the user data inside the class structure and then the getName() is something like this:

   private $name;
   
   // Load all user data inside the class' structure
   public function load() {
   
       $this->name = // MySQL query here
   }
   
   public function getName() {
   
       return $this->name;
   }
   

I thought, not sure if mistakenly or not, that the first way is more efficient because i only get the data I need, while the second way is more OOP but less efficient.

So, here's the question: what is the better way? Why? Are there better ways?

Either way, consider storing/caching the results of that so you do not make a query every time you use getName on that object. Also, consider not wrrying about all that by using a ORM/DBAL Solution like propel or doctrine.

Also check out Lazy Loading and the Active Record Pattern

Run your query just in time and only run it once (unless you know the value might change), try something like the following:

 class User {
   protected $data;

   function getName()
   {
     if (!isset($data['name'])) {
       // if you can load more than just $this->data['name'] in one query
       // you probably should.
       $this->data['name'] = // query here
     }
     return $this->data['name'];
   }

 }

Aside from the question being kinda broad (as there are countless patterns), the second way you mentioned is better IMO, and to add to it I would also suggest supplying ID as a parameter which you could then use to build a single query to fetch the user by ID and then manually assign all properties (from the fetched row).