What is PHP?

PHP, which stands for "Hypertext Preprocessor", is a server-side, HTML embedded scripting language used to create dynamic Web pages. Much of its syntax is borrowed from C, Java and Perl with some unique features thrown in. The goal of the language is to allow Web developers to write dynamically generated pages quickly. In an HTML page, PHP code is enclosed within special PHP tags.

When a visitor opens the page, the server processes the PHP code and then sends the output (not the PHP code itself) to the visitor's browser. It means that, unlike JavaScript, you don't have to worry that someone can steal your PHP script. PHP offers excellent connectivity to many databases including MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, and Generic ODBC. The popular PHP-MySQL combination (both are open-source products) is available on almost every UNIX host. Being web-oriented, PHP also contains all the functions to do things on the Internet - connecting to remote servers, checking email via POP3 or IMAP, url encoding, setting cookies, redirecting, etc.

PHP scripting

PHP is now officially known as "PHP: HyperText Preprocessor". It is a server-side scripting language usually written in an HTML context. Unlike an ordinary HTML page, a PHP script is not sent directly to a client by the server; instead, it is parsed by the PHP binary or module, which is server-side installed. HTML elements in the script are left alone, but PHP code is interpreted and executed.

PHP code in a script can query databases, create images, read and write files, talk to remote servers – the possibilities are endless. The output from PHP code is combined with the HTML in the script and the result sent to the user?s web-browser, therefore it can never tell the user whether the web-server uses PHP or not, because all the browser sees is HTML. PHP's support for Apache and MySQL further increases its popularity.

Apache is now the most-used web-server in the world, and PHP can be compiled as an Apache module. MySQL is a powerful free SQL database, and PHP provides a comprehensive set of functions for working with it. The combination of Apache, MySQL and PHP is all but unbeatable. That doesn?t mean that PHP cannot work in other environments or with other tools. In fact, PHP supports an extensive list of databases and web-servers. The rise in popularity of PHP has coincided with a change of approach in web-publishing. While in the mid-1990s it was ok to build sites, even relatively large sites, with hundreds of individual hard-coded HTML pages, today?s webmasters are making the most of the power of databases to manage their content more effectively and to personalize their sites according to individual user preferences.

Reasons for using PHP

There are some indisputable great reasons to work with PHP. As an open source product, PHP is well supported by a talented production team and a committed user community. Furthermore, PHP can be run on all the major operating systems with most servers.

The speed of development is also important. Because PHP allows you to separate HTML code from scripted elements, you will notice a significant decrease in development time on many projects. In many instances, you will be able to separate the coding stage of a project from the design and build stages. Not only can this make life easier for you as a programmer, but it also can remove obstacles that stand in the way of effective and flexible design. Well-maintained open source projects offer users additional benefits.

You benefit from an accessible and committed community who offer a wealth of experience in the subject, as fast and as cheap as possible. Chances are that any problem you encounter in your coding can be answered swiftly and easily with a little research. If that fails, a question sent to a mailing list or forum can have an intelligent, authoritative response. You also can be sure that bugs will be addressed as they are found, and that new features will be made available as the need is defined. You will not have to wait for the next commercial release before taking advantage of improvements, and there is no hidden interest in a particular server product or operating system. You are free to make choices that suit your needs or those of your clients and incorporate whatever components you want.

What can PHP do?

Anything. PHP is mainly focused on server-side scripting, so you can do anything any other CGI program can do, such as collect form data, generate dynamic page content, or send and receive cookies. But PHP can do much more.
There are three main areas where PHP scripts are used.

• Server-side scripting. This is the most traditional and main target field for PHP. You need three things to make this work. The PHP parser (CGI or server module), a web server and a web browser. You need to run the web server, with a connected PHP installation. You can access the PHP program output with a web browser, viewing the PHP page through the server. All these can run on your home machine if you are just experimenting with PHP programming. See the installation instructions section for more information.
• Command line scripting. You can make a PHP script to run it without any server or browser. You only need the PHP parser to use it this way. This type of usage is ideal for scripts regularly executed using cron (on *nix or Linux) or Task Scheduler (on Windows). These scripts can also be used for simple text processing tasks. See the section about Command line usage of PHP for more information.
• Writing desktop applications. PHP is probably not the very best language to create a desktop application with a graphical user interface, but if you know PHP very well, and would like to use some advanced PHP features in your client-side applications you can also use PHP-GTK to write such programs. You also have the ability to write cross-platform applications this way. PHP-GTK is an extension to PHP, not available in the main distribution. If you are interested in PHP-GTK, visit » its own website.

PHP can be used on all major operating systems, including Linux, many Unix variants (including HP-UX, Solaris and OpenBSD), Microsoft Windows, Mac OS X, RISC OS, and probably others. PHP has also support for most of the web servers today. This includes Apache, Microsoft Internet Information Server, Personal Web Server, Netscape and iPlanet servers, Oreilly Website Pro server, Caudium, Xitami, OmniHTTPd, and many others. For the majority of the servers, PHP has a module, for the others supporting the CGI standard, PHP can work as a CGI processor.

So with PHP, you have the freedom of choosing an operating system and a web server. Furthermore, you also have the choice of using procedural programming or object oriented programming, or a mixture of them. Although not every standard OOP feature is implemented in PHP 4, many code libraries and large applications (including the PEAR library) are written only using OOP code. PHP 5 fixes the OOP related weaknesses of PHP 4, and introduces a complete object model.
With PHP you are not limited to output HTML. PHP's abilities includes outputting images, PDF files and even Flash movies (using libswf and Ming) generated on the fly. You can also output easily any text, such as XHTML and any other XML file. PHP can autogenerate these files, and save them in the file system, instead of printing it out, forming a server-side cache for your dynamic content.
One of the strongest and most significant features in PHP is its support for a wide range of databases. Writing a database-enabled web page is incredibly simple. The following databases are currently supported:

• Adabas D
• dBase
• Empress
• FilePro (read-only)
• Hyperwave
• IBM DB2
• Informix
• Ingres
• InterBase
• FrontBase
• mSQL
• Direct MS-SQL
• MySQL
• ODBC
• Oracle (OCI7 and OCI8)
• Ovrimos
• PostgreSQL
• SQLite
• Solid
• Sybase
• Velocis
• Unix dbm

We also have a database abstraction extension (named PDO) allowing you to transparently use any database supported by that extension. Additionally PHP supports ODBC, the Open Database Connection standard, so you can connect to any other database supporting this world standard. PHP also has support for talking to other services using protocols such as LDAP, IMAP, SNMP, NNTP, POP3, HTTP, COM (on Windows) and countless others.

You can also open raw network sockets and interact using any other protocol. PHP has support for the WDDX complex data exchange between virtually all Web programming languages. Talking about interconnection, PHP has support for instantiation of Java objects and using them transparently as PHP objects. You can also use our CORBA extension to access remote objects. PHP has extremely useful text processing features, from the POSIX Extended or Perl regular expressions to parsing XML documents.

For parsing and accessing XML documents, PHP 4 supports the SAX and DOM standards, and you can also use the XSLT extension to transform XML documents. PHP 5 standardizes all the XML extensions on the solid base of libxml2 and extends the feature set adding SimpleXML and XMLReader support. At last but not least, we have many other interesting extensions, the mnoGoSearch search engine functions, the IRC Gateway functions, many compression utilities (gzip, bz2, zip), calendar conversion, translation... As you can see this page is not enough to list all the features and benefits PHP can offer. Read on in the sections about installing PHP, and see the function reference part for explanation of the extensions mentioned here.

Reasons for using PHP

There are some indisputable great reasons to work with PHP. As an open source product, PHP is well supported by a talented production team and a committed user community. Furthermore, PHP can be run on all the major operating systems with most servers.

The speed of development is also important. Because PHP allows you to separate HTML code from scripted elements, you will notice a significant decrease in development time on many projects. In many instances, you will be able to separate the coding stage of a project from the design and build stages. Not only can this make life easier for you as a programmer, but it also can remove obstacles that stand in the way of effective and flexible design. Well-maintained open source projects offer users additional benefits.

You benefit from an accessible and committed community who offer a wealth of experience in the subject, as fast and as cheap as possible. Chances are that any problem you encounter in your coding can be answered swiftly and easily with a little research. If that fails, a question sent to a mailing list or forum can have an intelligent, authoritative response. You also can be sure that bugs will be addressed as they are found, and that new features will be made available as the need is defined. You will not have to wait for the next commercial release before taking advantage of improvements, and there is no hidden interest in a particular server product or operating system. You are free to make choices that suit your needs or those of your clients and incorporate whatever components you want.

What is mysql?

MySQL, the most popular Open Source SQL database management system, is developed, distributed, and supported by Sun Microsystems, Inc.
The MySQL Web site (http://www.mysql.com/) provides the latest information about MySQL software.

• MySQL is a database management system.

A database is a structured collection of data. It may be anything from a simple shopping list to a picture gallery or the vast amounts of information in a corporate network. To add, access, and process data stored in a computer database, you need a database management system such as MySQL Server. Since computers are very good at handling large amounts of data, database management systems play a central role in computing, as standalone utilities, or as parts of other applications.

• MySQL is a relational database management system.

A relational database stores data in separate tables rather than putting all the data in one big storeroom. This adds speed and flexibility. The SQL part of “MySQL” stands for “Structured Query Language.” SQL is the most common standardized language used to access databases and is defined by the ANSI/ISO SQL Standard. The SQL standard has been evolving since 1986 and several versions exist. In this manual, “SQL-92” refers to the standard released in 1992, “SQL:1999” refers to the standard released in 1999, and “SQL:2003” refers to the current version of the standard. We use the phrase “the SQL standard” to mean the current version of the SQL Standard at any time.

• MySQL software is Open Source.

Open Source means that it is possible for anyone to use and modify the software. Anybody can download the MySQL software from the Internet and use it without paying anything. If you wish, you may study the source code and change it to suit your needs. The MySQL software uses the GPL (GNU General Public License), http://www.fsf.org/licenses/, to define what you may and may not do with the software in different situations. If you feel uncomfortable with the GPL or need to embed MySQL code into a commercial application, you can buy a commercially licensed version from us. See the MySQL Licensing Overview for more information (http://www.mysql.com/company/legal/licensing/).

• The MySQL Database Server is very fast, reliable, and easy to use.

If that is what you are looking for, you should give it a try. MySQL Server also has a practical set of features developed in close cooperation with our users. You can find a performance comparison of MySQL Server with other database managers on our benchmark page. See Section 7.1.4, “The MySQL Benchmark Suite”.
MySQL Server was originally developed to handle large databases much faster than existing solutions and has been successfully used in highly demanding production environments for several years. Although under constant development, MySQL Server today offers a rich and useful set of functions. Its connectivity, speed, and security make MySQL Server highly suited for accessing databases on the Internet.

• MySQL Server works in client/server or embedded systems.

The MySQL Database Software is a client/server system that consists of a multi-threaded SQL server that supports different backends, several different client programs and libraries, administrative tools, and a wide range of application programming interfaces (APIs).
We also provide MySQL Server as an embedded multi-threaded library that you can link into your application to get a smaller, faster, easier-to-manage standalone product.

• A large amount of contributed MySQL software is available.

It is very likely that your favorite application or language supports the MySQL Database Server.The official way to pronounce “MySQL” is “My Ess Que Ell” (not “my sequel”), but we do not mind if you pronounce it as “my sequel” or in some other localized way.