OOP principles were difficult for me to grasp because for some reason I could never apply them to web development. As I developed more and more projects I started understanding how some parts of my code could use certain design patterns to make them easier to read, reuse, and maintain so I started to use it more and more.
The one thing I still can't quite comprehend is why I should abstract my data layer. Basically if I need to print a list of items stored in my DB to the browser I do something along the lines of:
$sql = 'SELECT * FROM table WHERE type = "type1"';'
$result = mysql_query($sql);
while($row = mysql_fetch_assoc($result))
{
echo '<li>'.$row['name'].'</li>';
}
I'm reading all these How-Tos or articles preaching about the greatness of PDO but I don't understand why. I don't seem to be saving any LoCs and I don't see how it would be more reusable because all the functions that I call above just seem to be encapsulated in a class but do the exact same thing. The only advantage I'm seeing to PDO are prepared statements.
I'm not saying data abstraction is a bad thing, I'm asking these questions because I'm trying to design my current classes correctly and they need to connect to a DB so I figured I'd do this the right way. Maybe I'm just reading bad articles on the subject :)
I would really appreciate any advice, links, or concrete real-life examples on the subject!
One of the other advantage of abstracting the data layer is to be less dependent on the underlying database.
With your method, the day you want to use something else than mysql or your column naming change or the php API concerning mysql change, you will have to rewrite a lot of code.
If all the database access part was neatly abstracted, the needed changes will be minimal and restricted to a few files instead of the whole project.
It is also a lot easier to reuse code concerning sql injection or others utility function if the code is centralized in one place.
Finally, it's easier to do unit testing if everything goes trough some classes than on every pages from your project.
For example, in a recent project of mine (sorry, no code sharing is possible), mysql related functions are only called in one class. Everything from query generation to object instantiation is done here. So it's very for me to change to another database or reuse this class somewhere else.