July 15, 2009
Database designing is always tricky no matter how expert you are on the subject. Unfortunately, most of the time developers just want to concentrate on the programming side of the websites and focus less on one of the most important components of the web: the database (actually, it IS the main component of the web).
Sure you can go ahead and start designing tables and filling them out with data, but carefully planned databases will help you a lot in the long run, especially when you want to grow your service. Here’s a nice article by Antonio Lupetti where he points out 10 useful articles about database design.
July 6, 2009
A supposedly underrated topic for SQL enthusiasts, Transactions are a vital part of any SQL query.
Suppose that for whatever reason, the second update statement should update exactly five rows. If @@ROWCOUNT, which hold the number of rows affected by each statement, is five then the transaction commits otherwise it rolls back. The ROLLBACK TRAN statement “undoes” all the work since the matching BEGIN TRAN statement. It will not perform either update statement. Note that Query Analyzer will show you messages indicating that rows were updated but you can query the database to verify that no actual data modifications took place.
June 26, 2009
Originating from architectural design (as in design of buildings), when design patterns crossed over to computer programming in the 1980’s, only a small group of people using a language called “SmallTalk” were applying them. In 1995, a group of four authors released a book called “Design Patterns: Elements of Reusable Object-Oriented Software”.
The four authors where nicked the “Gang of Four”. SmallTalk, but also C++ where the languages applying design patterns at that time. It is still the most respected book on design patterns to this date. “Gang of Four” (abbr. GoF) is also commonly used to refer to the book, rather than the authors.
Soon after, ‘Gurus’ such as Martin Fowler started publishing their own works, perhaps most notably “Patterns of Enterprise Application Architecture” (abbr. PoEAA). By then, most books where using Java in their examples. The Java community has played a big part in the evolution of Design Patterns, not in the last place thanks to efforts from Alur et al. with their “J2EE Core Patterns”.
June 26, 2009
Nowadays it’s a quite common approach to have models that essentially just represent database tables, and may support saving the model instance right to the database. While the ActiveRecord pattern and things like Doctrine are useful, you may sometimes want to decouple the actual storage mechanism from the rest of the code.
This is where the Data Access Object pattern comes in. It’s a pattern which abstracts the details of the storage mechanism – be it a relational database, OO database, an XML file or whatever. The advantage of this is that you can easily implement different methods to persist objects without having to rewrite parts of your code.
I’m again going to use the programming language quiz game I wrote as an example. Since I initially wrote it to use Doctrine ORM directly, and both the old and new code are available, you can easily see how the code was improved.
June 24, 2009
Tony Marston gives a nice intro to OOP:
The problem with OOP is that there is no clear definition of what it is and what it is not. Since its first appearance numerous people have expanded on its original definition (whatever that was) and invented new ‘rules’ which in turn have been subject to different interpretations. For each interpretation there are also many different possible implementations. There is no single definition, or set of definitions, which is universally accepted, therefore, no matter what you do, somebody somewhere will always find a reason to complain that ‘you are wrong!’
This article is highly recommended if you want to know the basics of OOP and also the intermediate level of OO programming.
June 24, 2009
This article by Tony Marston is an important one since it deals with the best practices of OO programming. I could say the article is not language specific but since he mostly deals with PHP and MySQL, the codes are based on PHP. Describes topics such as Data Dictionary, Entities, and OOP pagination system. He also shows how to store the state of an object in one page and then “resume” that state in another PHP script by using PHP’s built-in session object. Pretty neat, huh?
June 20, 2009
Database connectivity is one of the most important columns of a dynamic web. Besides being able to handle database queries with great flexibility, a website must provide the database with strong security. One solution is to write some thousands of lines codes and repeat the process for future projects OR use a single class to handle all the database functions for all your projects. Since I have one of the most powerful assets a good programmer must have that is, laziness, I would opt for the second option.
This article from Particletree.com provides a solid background for creating really flexible database classes that you can extend in the future. Also, they provide the article for three different languages (although you can adapt the idea for almost infinite number of languages). Enjoy!