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    <p>I guess there are actually two items in the question:</p> <ol> <li><p>As @duskwuff points out, there is nothing wrong with static methods per-se; if you know their caveats (e.g. "<a href="http://php.net/manual/en/language.oop5.late-static-bindings.php" rel="nofollow">Late Static Binding</a>") and limitations, they are just another tool to work with. However, the way you model the interaction with the DB does have an impact on separation of concerns and, for example, unit testing. </p></li> <li><p>For different reasons there is no "absolute proper way" of doing persistence. One of the reasons is that each way of tackling it has different tradeoffs; which one is better for you project is hard to tell. The other important reason is that languages evolve, so a new language feature can improve the way frameworks handle things. So, instead of looking for the perfect way of doing it you may want to consider different ways of approaching OO persistence assuming that you want so use a relational database:</p> <ul> <li>Use the <a href="http://en.wikipedia.org/wiki/Active_record_pattern" rel="nofollow">Active Record</a> pattern. What you have done so far looks like is in the Active Record style, so you may find it natural. The active record has the advantage of being simple to grasp, but tends to be tightly coupled with the DB (of course this depends on the implementation). This is bad from the separation of concerns view and may complicate testing.</li> <li>Use an ORM (like <a href="http://www.doctrine-project.org/" rel="nofollow">Doctrine</a> or <a href="http://www.propelorm.org/" rel="nofollow">Propel</a>). In this case most of the hard work is done by the framework (BD mapping, foreign keys, cascade deletes, some standard queries, etc.), but you must adapt to the framework rules (e.g. I recall having a lot of problems with the way Doctrine 1 handled hierarchies in a project. AFAIK this things are solved in Doctrine 2).</li> <li>Roll your own framework to suite your project needs and your programming style. This is clearly a time consuming task, but you learn a lot.</li> </ul></li> </ol> <p>As a general rule of thumb I try to keep my domain models as independent as possible from things like DB, mainly because of unit tests. Unit tests should be running all the time while you are programming and thus they should run fast (I always keep a terminal open while I program and I'm constantly switching to it to run the whole suite after applying changes). If you have to interact with the DB then your tests will become slow (any mid-sized system will have 100 or 200 test methods, so the methods should run in the order of milliseconds to be useful). </p> <p>Finally, there are different techniques to cope with objects that communicate with DBs (e.g. mock objects), but a good advise is to always have a layer between your domain model and the DB. This will make your model more flexible to changes and easier to test.</p> <p>EDIT: I forgot to mention the <a href="http://en.wikipedia.org/wiki/Data_access_object" rel="nofollow">DAO</a> approach, also stated in @MikeSW answer.</p> <p>HTH</p>
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    1. POWhere would a senior PHP developer locate the method getActiveEntries()?
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    1. USAndrés Fortier
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    1. COOk wow! Thanks for the detailed answer. Now I am trying to figure out which method would be best for someone that wants to learn the best route to become a senior php developer. I basically am trying to learn only those things that I will use from here on out. For instance, if I use active records, I will use it once, and then move on to something that allows for less coupling. So I want to start out with the option that allows for the lowest coupling. Of those that you mentioned, which would you recommend for lowest coupling and highest cohesion?
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    2. COI don't recommend Active Record pattern, not for 'real' applications anyway. It's a quick'n'dirty way of doing things and it breaks the SoC principle.
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    3. COYou are welcome @darga! I learned the hard way and found it really instructive: first I did some manual mapping and reached the point where I couldn't scale anymore. Then I used active record style and then ORMs. I also used OODBs (in Smalltalk, I don't know if there is a OODB for PHP). Of course this was in a long timespan and different projects (some commercials, some in research and some in the academy). My general recommendation is to stick to what you find natural until you see that it doesn't scale or fit your needs anymore. Then you will "feel" the need to switch and you will know the
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