The SitePoint PHP blog has a new post today sharing what they (well the author, George Fekete) see as the top 18 critical oversights common to web development in recent years. While the examples are in PHP, the principles could apply across multiple other languages.

Over the past years I had the opportunity to work on some interesting projects, complex in nature with an ongoing development, constantly upgrading, refactoring and adding new features to them. This article will cover the biggest coding oversights most PHP developers make, when dealing with medium and large projects. Oversights such as not differentiating between development environments or not implementing caching and backup. [...] The root of these problems lies mainly in developers’ knowledge and experience, especially the lack of it.

He's broken them up into three different overall types: design, application and database levels. Included in his list are things like:

• Developing with error reporting off
• Not implementing caching
• Not using automated tests
• Not differentiating between read / write queries
• Not using transactions
• No backup
• No monitoring

Check out the full post for the rest of the items on the list, all including examples and explanations.

Justin Carmony recently put together a blog post looking at the biggest database design oversights that PHP developers can make in their applications.

I've thought of some of the biggest oversights I've had when working with PHP and MySQL and put them in a list. This is my personal list, and I'm sure some people can think of some other oversights that belong on the list as well. This list is just for PHP & MySQL, not PHP and any database. I know many people like using software like Doctrine to allow switching between different database types. That is beyond the scope of this article.

He includes a list of five - not having a data access layer, designing for only one database connection, not including developer logging, having queries written in procedural code and no separation of reads and writes to the database.