PHP is a powerful open source server-sided scripting language that can be used on a wide variety of operating systems and webservers, including Apache on UNIX and IIS on Windows.
PHP contains numerous extensions which enable you to dynamically create images and flash files, parse xml, connect to remote servers using pop, imap, ftp, http and raw sockets, natively access many database servers including PostgreSql, MySQL and Microsoft SQL Server, compress and decompress files, lookup domain names and and much more.
PHP has an excellent manual and online documentation which covers every function for every extension available.
If you have a directory which users can upload files into it’s a good idea for security reasons to disable server-side parsing of scripts such as PHP. This post shows a couple of options using Apache’s .htaccess files.
This is a summary of the posts I've written about PHP's file_get_contents functions when used to download remote content (e.g. webpages, XML files, images etc) and the CURL functions which are used to do the same thing.
PHP code in a script is commonly delimited by opening <?php and closing ?> tags but there are also the older short open tags like this <? There are instances where you may need to disable short tags as shown in this post and using an Apache .htaccess file.
When temporarily taking down a website to perform maintenance, it’s a good idea to return a "503 Service Temporarily Unavailable" header so search engines know to come back later. This post shows how to set this header using an Apache .htaccess file, and also how to show a response page to users with PHP so they know to try again later.
PHP’s Data Objects, known as PDO, are well covered in the PHP online documentation here but the format of the DSN connection string is covered individually for each driver so I’ve summarised them here in this post for quick reference.
PHP’s PDO database abstraction class offers a better way to connect to databases than the mysql_* etc style functions, or using a 3rd party database library. This post looks at handle errors when connecting and a follow up post later this week will look at how to check for errors when running individual queries after a connection has been successfully established.