You may have been using relational databases in your PHP applications for a long time (PHP loves MySQL after all) but you might not have ever dug deep enough to understand how those databases work internally. In this detailed tutorial from Coding Geek they dive way in and cover everything from the basics out to complex sorting, management components and query handling.

When it comes to relational databases, I can’t help thinking that something is missing. They’re used everywhere. [...] you can google by yourself “how does a relational database work” to see how few results there are. [...] Are relational databases too old and too boring to be explained outside of university courses, research papers and books?

As a developer, I HATE using something I don’t understand. And, if databases have been used for 40 years, there must be a reason. [...] Over the years, I’ve spent hundreds of hours to really understand these weird black boxes I use every day. Relational Databases are very interesting because they’re based on useful and reusable concepts. If understanding a database interests you but you’ve never had the time or the will to dig into this wide subject, you should like this article.

He covers a wide range of topics during the post:

• O(1)) vs O(n2) (or how data sets are handled based on size)
• Array, Tree and Hash table
• Global overview (structure of the database system and its pieces)
• Query manager
• Statistics (and optimizing storage of the data)
• Data manager
• Deadlock
• Logging

Each of these topics comes with a lot of explanation, examples of how the internals are functioning as well as diagrams to help make a bit more sense. If you've ever really wanted to know how that database you use functions, this is definitely the article to check out.

In another of his series looking "under the covers" at what actually happens in the PHP language during its use, Sharif Ramadan has posted this look at the object handling in PHP's OOP functionality.

I would love to take a good long look under the hood at just how PHP objects and classes do the work that they do, and hope that you could benefit from that knowledge. [There are] many questions that come across my desk, on a regular basis, from developers and beginner PHP enthusiasts that I’ve worked with over the years, and are some of the key points this article attempts to help you answer.

He talks about classes "giving birth" to objects, how they're stored internal to PHP and how they provide the "blueprints" for it to lay out the storage of the object's data. He talks about using identifiers for variable/property access, object handlers and how "$this" fits into all of it. He notes that OOP, while a major part of PHP now, wasn't in the initial versions (until around PHP4). He finishes off the post talking about lateral/vertical context switching, the lifecycle of an object and the "early binding problem" and class scope.

In this new post to the Web Mozarts site, Bernhard talks about the architecture behind the current Symfony2 forms implementation and how it handles the requests your forms make.

Symfony2 features a brand-new Form component that, to my knowledge, supersedes most existing PHP form libraries in functionality and extensibility (not counting the still lacking, native JavaScript support). [...] The purpose of this post is to demonstrate that the Symfony2 Form component is perfectly suited for this requirement. Symfony2-specific functionality can be unplugged, leaving only the raw core dealing with form processing and abstraction.

The post is broken up into several different sections, each detailing a different aspect of this Forms functionality:

• It's influences from other frameworks
• Key aspects it provides
• Abstraction (reusable code)
• Extensibility
• Compositionality
• Separation of Concerns
• Model Binding
• Dynamic Behavior

Both a high-level architecture and low-level architecture are provided, showing you the internal flow behind the form handling. You can find out more about this component in the Symfony manual or peek into the code on github.