Wiley PHP5 and MySQL Bible
Contents
1. and there can be limits to the number of concurrent pro cesses that can be running at any one time Other CGI scripting languages such as Perl and Tcl can be quite slow Most Web sites have moved away from use of CGI for performance and security reasons Although it takes a slight performance hit by being interpreted rather than compiled this is far outweighed by the benefits PHP derives from its status as a Web server module When compiled this way PHP becomes part of the http daemon itself Because there is no transfer to and from a separate application server as there is with ColdFusion for instance requests can be filled with maximum efficiency Although no extensive formal benchmarks have compared the two much anecdotal evidence and many small benchmarks suggest that PHP is at least as fast as ASP and readily outperforms ColdFusion or JSP in most applications 03 557467 ch01 qxd 4 5 04 11 06 AM Page 13 F Chapter 1 Why PHP and MySQL 13 Open source licensing We ve already dealt with the cost advantages of open source software in the Cost section of this chapter The other major consequence of these licenses is that the complete source code for the software must be included in any distribution In fact the Unix version of PHP is released only as source code so far the development team has staunchly resisted countless pleas to distribute official binaries for any of the Unixes At first new users particularly th2. where one or more developers decide to release a sepa rate complete version of a piece of software this practice is referred to as code forking If somewhere down the road you develop irreconcilable differences with the PHP develop ment team you can take every bit of code they ve labored over for all these years and use it as the basis of your own product You couldn t call it PHP and you d have to include stuff in your documentation that gave due credit to the authors the rationale is that source code distributions make it next to impossible for any single person or group to hijack a program to the detriment of the community as a whole because every user always has the power to take the source and walk Users new to the open source model should be aware that this right is also enjoyed by the developers At any time Rasmus Zend and company can choose to defect from the commu nity and put all their future efforts into a commercial or competing product based on PHP Of course the codebase up to this point would still be available to anyone who wanted to pick up the baton and for a product as large as PHP that could be a considerable number of vol unteer developers This leads to one other oft forgotten advantage of open source software You can be pretty sure the software will be around in a few years no matter what In these days of products with the life spans of morning glories it s hard to pick a tool with staying power Fa
3. MySQL s creator Monty Widenius worked for a Swedish IT and data consulting firm TcX While at TcX Monty authored UNIREG a terminal interface builder that connected to raw ISAM data stores In the intervening 15 years UNIREG served its makers rather well through a series of translations and extensions to accommodate increasingly large data sets In 1994 when TcX began working on Web data applications chinks in the UNIREG armor primarily having to do with application overhead began to appear This sent Monty and his colleagues off to look for other tools One they inspected rather closely was Hughes mSQL a light and zippy database application developed by David Hughes mSQL possessed the dis tinct advantages of being inexpensive and somewhat entrenched in the market as well as featuring a fairly well developed client API The 1 0 series of mSQL release lacked indexing however a feature crucial to performance with large data stores Although the 2 0 series of mSQL would see the addition of this feature the particular implementation used was not compatible with UNIREG s B based features At this point MySQL at least conceptually was born 03 557467 ch01 qxd 4 5 04 11 06 AM Page 6 e 6 Part PHP The Basics Monty and TeX decided to start with the substantial work already done on UNIREG while developing a new API that was substantially similar to that used by mSQL with the exception of the more effective UNIREG indexing sche
4. and real PHP community members might tell you to read the manual take your question over to the appropriate database mailing list or just stop your whining but they ll never tell you to wipe your C drive and then charge you for the privilege Often they ll look at your code and tell you what you re doing wrong or even help you design an application from the ground up As you become more comfortable with PHP you may wish to contribute Bug tracking offer ing advice to others on the mailing lists posting scripts to public repositories editing docu mentation and of course writing C code are all ways you can give back to the community MySQL while open source licensed for nonredistributive uses is somewhat less community driven in terms of its development Nevertheless it benefits from a growing community of users who are actively listened to by the development team Rarely has a software project responded so vigorously to community demand And the community of users can be extremely responsive to other users who need help It s a point of pride with a lot of SQL gurus that they can write the complicated queries that get you the results you are looking for but had struggled with for days In many cases they ll help you for nothing more than the enduring if small fame that comes with the archived presence of their name on Google Groups Try comparing that with 100 per incident support Summary PHP and MySQL individually o
5. codebase but charge you for use of the product at the end Caution Don t even think about coming back with a riposte that involves violating a software license we re covering our ears we re not listening Especially with the explosion in no cost software there s just no good reason to break the law Besides it s bad karma for software developers What goes around comes around don t ya know For all their openness the licenses for MySQL and PHP are quite different You should not assume that you understand the MySQL terms simply because you have read the PHP license They have many similarities to be sure but also some radically different provisions especially when it comes to when you should pay Table 1 3 shows examples of the various source and fee positions in today s software marketplace Table 1 3 Source Fee Spectrum Fee Structure Closed Source Controlled Source Open Source Fee for all uses Macromedia ColdFusion Fee for some uses Corel WordPerfect Sun Java MySQL No fee for any use Microsoft IE Sun StarOffice GPLed software 03 557467 ch01 qxd 4 5 04 11 06 AM Page 14 p 14 Part PHP The Basics Genuinely open source software like PHP cannot seek to limit the purposes for which it is used the people allowed to use it or a host of other factors The most critical of these rights is the one allowing users to make and distribute any modifications along with the original software In the most extreme case
6. one with over 100 000 entries and trouble ticket tracking systems In its newest incarnation PHP5 strives to deliver something many users have been clamoring for over the past few years much improved object oriented programming OOP functional ity PHP has long nodded to the object programming model with functions that allow object programmers to pull out results and information in a way familiar to them These efforts still fell short of the ideal for many programmers however and efforts to force PHP to build in fully object oriented systems often yielded unintended results and hurt performance PHP5 s newly rebuilt object model brings PHP more in line with other object oriented languages such as Java and C offering support for features such as overloading interfaces private mem ber variables and methods and other standard OOP constructions With the crash of the dot com bubble PHP is poised to be used on more sites than ever Demand for Web delivered functionality has decreased very little and emerging technological standards continue to pop up all the time but available funding for hardware licenses and especially headcount has drastically decreased In the post crash Web world PHP s shallow learning curve quick implementation of new functionality and low cost of deployment are hard arguments to beat The History of MySQL Depending on how much detail you want the history of MySQL can be traced as far back as 1979 when
7. the PHP3 and PHP4 parsers have also generalized and extended their work under the rubric of Zend com Zeev Andi Zend get it 03 557467 ch01 qxd 4 5 04 11 06 AM Page 5 F Chapter 1 Why PHP and MySQL The fourth quarter of 1998 initiated a period of explosive growth for PHP as all open source technologies enjoyed massive publicity In October 1998 according to the best guess just over 100 000 unique domains used PHP in some way Just over a year later PHP broke the one million domain mark When we wrote the first edition of this book in the first half of 2000 the number had increased to about two million domains As we write this approximately 15 million public Web servers in the software sense not the hardware sense have PHP installed on them Public PHP deployments run the gamut from mass market sites such as Excite Webmail and the Indianapolis 500 Web site which serve up millions of pageviews per day through mass niche sites such as Sourceforge net and Epinions com which tend to have higher functional ity needs and hundreds of thousands of users to e commerce and brochureware sites such as The Bookstore at Harvard com and Sade com Web home of the British singer which must be visually attractive and easy to update There are also PHP enabled parts of sites such as the forums on the Internet Movie Database imdb com and a large installed base of nonpublic PHP deployments such as LDAP directories MCI WorldCom built
8. 03 557467 ch01 qxd 4 5 04 11 06 AM Page 3 e CHAP E R Why PHP and MySQL In This Chapter Te first chapter is an introduction to PHP MySQL and the inter Understanding PHP and action of the two In it we ll try to address some of the most com MySQL mon questions about these tools such as What are they and How do they compare to similar technologies Most of the chapter is A history of PHP taken up with an enumeration of the many many reasons to choose PHP MySQL or the two in tandem If you re a techie looking for some A history of MySQL ammunition to lob at your PHB Pointy Haired Boss for those who don t know the Dilbert cartoons or a manager asking yourself what The benefits of using is this P whatever thing your geeks keep whining to get this chapter PHP and MySQL will provide some preliminary answers What Is PHP PHP is the Web development language written by and for Web devel opers PHP stands for PHP Hypertext Preprocessor The product was originally named Personal Home Page Tools and many people still think that s what the acronym stands for But as it expanded in scope anew and more appropriate albeit GNU ishly recursive name was selected by community vote PHP is currently in its fifth major rewrite called PHP5 or just plain PHP PHP and MySQL A competitive advantage PHP is a server side scripting language which can be embedded in HTML or used as a stand
9. Web server that runs about 67 percent of the World Wide Web according to the widely quoted Netcraft Web server survey This means that the PHP scripting engine can be built into the Web server itself leading to faster processing more efficient memory allocation and greatly simplified maintenance Like Apache Server PHP is fully cross platform meaning it runs native on sev eral flavors of Unix as well as on Windows and now on Mac OS X All projects under the aegis of the Apache Software Foundation including PHP are open source software What Is MySQL MySQL pronounced My Ess Q El is an open source SQL Relational Database Management System RDBMS that is free for many uses more detail on that later Early in its history MySQL occasionally faced opposition due to its lack of support for some core SQL constructs such as subselects and foreign keys Ultimately however MySQL found a broad enthusiastic user base for its liberal licensing terms perky performance and ease of use Its acceptance was aided in part by the wide variety of other technologies such as PHP Java Perl Python and the like that have encouraged its use through stable well documented modules and extensions MySQL has not failed to reward the loyalty of these users with the addition of both subselects and foreign keys as of the 4 1 series Databases in general are useful arguably the most consistently useful family of software products the killer produ
10. ability Their respective develop ment teams have thus far enjoyed a clear vision of their project and refused to be distracted by every new fad and ill thought out user demand that comes along Much of the effort goes into incremental performance improvements communicating with more major databases or adding better session support In the case of MySQL the addition of reasonable and expected new features has hit a rapid clip For both PHP and MySQL such improvements have rarely come at the expense of compatibility Applications written in PHP3 will function with little or no revision for PHP4 and 5 And because of the standards based SQL support MySQL 3 x databases are easily moved to more current versions and most likely always will be Speed PHP is pleasingly zippy in its execution especially when compiled as an Apache module on the Unix side The MySQL server once started executes even very complex queries with huge result sets in record setting time PHP5 is much faster for almost every use than CGI scripts There is an unfortunate grain of truth to the joke that CGI stands for Can t Go Instantly Although many CGI scripts are writ ten in C one of the lowest level and therefore speediest of the major programming languages they are hindered by the fact that each request must spawn an entirely new process after being handed off from the http daemon The time and resources necessary for this handoff and spawning are considerable
11. ally are You or your boss may therefore have some lingering doubts about the quality and viability of no cost software It probably doesn t help that until recently software that didn t cost money formerly called freeware shareware or free software was generally thought to fall into one of three categories Programs filling small uncommercial niches Programs performing grungy low level jobs Programs for people with bizarre socio political issues It s time to update some stereotypes once and for all We are clearly in the middle of a sea change in the business of software Much if not most major consumer software is dis tributed without cost today e mail clients Web browsers games and even full service office suites are all being given away as fast as their makers can whip up Web versions or set up FTP servers Consumer software is increasingly seen as a loss leader the flower that attracts the pollinating honeybee in other words a way to sell more server hardware operating systems connectivity advertising optional widgets or stock shares The full retail price of a piece of software therefore is no longer a reliable gauge of its quality or the eccentricity level of its user On the server side open source products have come on even stronger Not only do they compete with the best commercial stuff in many cases there s a feeling that they far exceed the competition Don t take our word for it As
12. alone binary although the former use is much more common Proprietary products in this niche are Microsoft s Active Server Pages Macromedia s ColdFusion and Sun s Java Server Pages Some tech journalists used to call PHP the open source ASP because its functionality is similar to that of the Microsoft product although this formulation was misleading as PHP was developed before ASP Over the past few years however PHP and server side Java have gained momentum while ASP has lost mindshare so this comparison no longer seems appropriate We ll explore server side scripting more thoroughly in Chapter 2 but for the moment you can think of it as a collection of super HTML tags or small programs that run inside your Web pages except on the server side before they get sent to the browser For example you can use PHP to add common headers and footers to all the pages ona site or to store form submitted data in a database 03 557467 ch01 qxd 4 5 04 11 06 AM Page 4 e 4 Part PHP The Basics Strictly speaking PHP has little to do with layout events on the fly DOM manipulation or really anything about what a Web page looks and sounds like In fact most of what PHP does is invisible to the end user Someone looking at a PHP page will not necessarily be able to tell that it was not written purely in HTML because usually the result of PHP is HTML PHP is an official module of Apache HTTP Server the market leading free
13. are diehard hand coders They tend to share certain gut level subcultural assumptions for instance that hand written code is beautiful and clean and maximally browser compatible and there fore the only way to go that they do not hesitate to express in vigorous terms The PHP community offers help and trades tips mostly by e mail and if you want to participate you have to be able to parse plain text source code with facility Some WYSIWYG users occasion ally ask list members to diagnose their problems by looking at their Web pages instead of their source code but this rarely ends well That said let us reiterate that PHP really is easy to learn and write especially for those with a little bit of experience in a C syntaxed programming language It s just a little more involved than HTML but probably simpler than JavaScript and definitely less conceptually complex than JSP or ASP NET 03 557467 ch01 qxd 4 5 04 11 06 AM Page 9 F Chapter 1 Why PHP and MySQL If you have no relational database experience or are coming from an environment such as Microsoft Access MySQL s command line interface and lack of implicit structure may at first seem a little daunting Again the word easy is relative However MySQL s increasingly faithful adherence to the ANSI SQL 92 standard and a comprehensive suite of external client pro grams coupled with graphical administration tools such as PHPMyAdmin and the new MySQL Control Center will get e
14. ct of modern computing Like many competing products both free and commercial MySQL isn t a database until you give it some structure and form You might think of this as the difference between a database and an RDBMS that is RDBMS plus user requirements equals a database There s lots more to say about MySQL but then again there s lots more space in which to say it The History of PHP Rasmus Lerdorf software engineer Apache team member and international man of mystery is the creator and original driving force behind PHP The first part of PHP was devel oped for his personal use in late 1994 This was a CGI wrapper that helped him keep track of people who looked at his personal site The next year he put together a package called the Personal Home Page Tools a k a the PHP Construction Kit in response to demand from users who had stumbled into his work by chance or word of mouth Version 2 was soon released under the title PHP FI and included the Form Interpreter a tool for parsing SQL queries By the middle of 1997 PHP was being used on approximately 50 000 sites worldwide It was clearly becoming too big for any single person to handle even someone as focused and ener getic as Rasmus A small core development team now runs the project on the open source benevolent junta model with contributions from developers and users around the world Zeev Suraski and Andi Gutmans the two Israeli programmers who developed
15. d a definition In ColdFusion you have to use tags developed by other people or go through the Custom Tag Extension development process As a witty PHP community member once said ColdFusion makes easy things easy and medium hard things impossible And as every programmer will agree once you experience the power of curly brackets and loops you never go back to tags 03 557467 chOl qxd 4 5 04 11 06 AM Page 12 p 12 Part PHP The Basics Stability The word stable means two different things in this context The server doesn t need to be rebooted often The software doesn t change radically and incompatibly from release to release To our advantage both of these connotations apply to both MySQL and PHP Apache Server is generally considered the most stable of major Web servers with a reputation for enviable uptime percentages Although it is not the fastest nor the easiest to administer once you get it set up Apache HTTP Server seemingly never crashes It also doesn t require server reboots every time a setting is changed at least on the Unix side PHP inherits this reliability plus its own implementation is solid yet lightweight In a two and a half month head to head test conducted by the Network Computing labs in October 1999 Apache Server with PHP handily beat both IIS Visual Studio and Netscape Enterprise Server Java for stability of environment PHP and MySQL are also both stable in the sense of feature st
16. disk to the customer You can also charge anything the market will bear for being willing to perform certain services or accept certain risks that the development team may not wish to undertake For instance you 03 557467 ch01 qxd 4 5 04 11 06 AM Page 8 F 8 Part PHP The Basics are allowed to charge money for guaranteeing that every copy of the software you distribute will be virus free or of reasonable quality taking on the risk of being sued if a bunch of cus tomers get bad CD ROMs that contain hard drive erasing viruses Usually open source software users can freely choose the precisely optimal cost benefit equation for each particular situation no cost and no warranties or expensive but well sup ported or something in between No organized attempt has been made yet to sell service and support for PHP although presumably that will be one of the value adds of Zend MySQL AB does sell support as part some of its licensing packages for the MySQL product Other open source products such as Linux have companies such as Red Hat standing by to answer your questions but the commercialization process is still in the early stages for PHP Ease of Use PHP is easy to learn compared to the other ways to achieve similar functionality Unlike Java Server Pages or C based CGI PHP doesn t require you to gain a deep understanding of a major programming language before you can make a trivial database or remote server call Unlike P
17. erl which has been semijokingly called a write only language PHP has a syntax that is quite easy to parse and human friendly And unlike ASP NET PHP is stable and ready to solve your problems today Many of the most useful specific functions such as those for opening a connection to an Oracle database or fetching e mail from an IMAP server are predefined for you A lot of complete scripts are waiting out there for you to look at as you re learning PHP In fact it s entirely possible to use PHP just by modifying freely available scripts rather than starting from scratch you ll still need to understand the basic principles but you can avoid many frustrating and time consuming minor mistakes We must mention one caveat Easy means different things to different people and for some Web developers it has come to connote a graphical drag and drop What You See Is What You Get development environment To become truly proficient at PHP you need to be comfort able editing HTML by hand You can use WYSIWYG editors to design sites format pages and insert client side features before you add PHP functionality to the source code There are even ways which we ll detail in Chapter 3 to add PHP functions to your favorite editing envi ronment It s not realistic however to think you can take full advantage of PHP s capabilities without ever looking at source code Most advanced PHP users including most of the development team members
18. ers of proprietary Web development technologies can sometimes be frustrated by the glacial speed at which new features are added to the official product standard to support emerging technologies With PHP this is not a problem All it takes is one developer a C compiler and a dream to add important new functionality This is not to say that the PHP 03 557467 ch01 qxd 4 5 04 11 06 AM Page 15 cb Chapter 1 Why PHP and MySQL 15 team will accept every random contribution into the official distribution without community buy in but independent developers can and do distribute their own extensions which may be later folded into the main PHP package in more or less unitary form For instance Dan Libby s elegant xmlrpc epi extension was adopted as part of the PHP distribution in version 4 1 a few months after it was first released as an independent package PHP development is also constant and ongoing Although there are clearly major inflection points such as the transition between PHP4 and PHP5 these tend to be most important deep in the guts of the parser people were actually working on major extensions throughout the transition period without critical problems Furthermore the PHP group subscribes to the open source philosophy of release early release often which gives developers many oppor tunities to follow along with changes and report bugs Compare this release scheme to the NET transition which has left developers wit
19. etary standards attempts to establish them clashes between them their benefits and draw backs for the consumer and how they are eventually replaced with new standards But in the past few years the Internet has demonstrated the great convenience of voluntary standards based platform independent compatibility E mail for example works so well because it enjoys a clear firm standard to which every program on every platform must conform New developments that break with the standard for example HTML based e mail stationery are generally regarded as deviations and their users find themselves having to bear the burdens of early adoption Furthermore customers especially the big fish businesses with large systems are fed up with spending vast sums to conform to a proprietary standard only to have the market uptake not turn out as promised Much of the current momentum toward XML and Web ser vices is driven by years of customer disappointment with Java RMI CORBA COM and even older proprietary methods and data formats Right now software developers are in a period of experimentation and flux concerning propri etary versus open standards Companies want to be sure they can maintain profitability while adopting open standards There have been some major legal conflicts related to proprietary standards which are still being resolved These could eventually result in mandated changes to the codebase itself or even affect the futures of t
20. growth in the number of domains As Web sites become even more ubiq uitous and as more of them go beyond simple static HTML pages PHP is expected to gain ground quickly in absolute numbers of users Although it s somewhat more difficult to get firm figures it seems that PHP is also in a strong position relative to similar products According to a 2002 Zend report Microsoft Active Server Pages technology appears to be utilized on about 24 percent of Web servers whereas ColdFusion is implemented on approximately 4 percent of surveyed domains PHP is used on over 24 percent of all Web servers as measured by a larger and more accurate sample and is now said to be the most popular server side scripting language on the Web Active Server Pages and ColdFusion used to be highly visible because they tended to be dis proportionately selected by large e commerce sites However the realities of the Web finally caught up with us and it is the flashy e commerce sites that were disproportionately thinned by the dot bomb crash It is now becoming clearer that most Web sites are informa tional rather than direct revenue centers and therefore do not repay high development expenses in an immediate way PHP enjoys substantial advantages over its competitors in this development category which has turned out to be the majority of the Internet Not proprietary The history of the personal computer industry to date has largely been a chronicle of propri
21. h almost a year in which Microsoft is not really improving IIS but has not yet released a prime time version of NET server It hasn t always been the case that MySQL added new features in a timely fashion It would probably be fair to say that a significant chunk of PostgreSQL users are former MySQL users frustrated by the lack of transaction support for example However the 4 0 and 4 1 versions have remedied this and other inequities Transactions are in the software today while subse lects and foreign keys are experimental but coming along nicely Popularity PHP is fast becoming one of the most popular choices for so called two tier development Web plus data Figure 1 2 charts growth since 1999 E PHP PHP Usage Stats Microsoft Internet Explorer ea x File Edit Yiew Favorites Tools Help Back gt A A Bsearch fyravorites meda 4 D Simi a S a address hetosiimwnohp netiusageehe is Usage Stats for November 2003 PHP 14 528 748 Domains 1 328 604 IP Addresses Source Netcraft PHP Usage for Nov 2003 16000000 12000000 10000000 8000000 6000000 4000000 2000000 EP PLEEL SHOPS SSS OSTA OOO 4 E Done Figure 1 2 Netcraft survey of PHP use 03 557467 ch01 qxd 4 5 04 11 06 AM Page 16 p 16 Part PHP The Basics Although it s not evident from this graphic the period October 1998 through October 1999 showed 800 percent
22. he companies involved In the face of all this uncertainty a growing number of businesses are attracted to solutions that they know will not have these problems in the foreseeable future PHP is in a position of maximum flexibility because it is so to speak antiproprietary It is not tied to any one server operating system unlike Active Server Pages It is not tied to any pro prietary cross platform standard or middleware as Java Server Pages or ColdFusion are It is not tied to any one browser or implementation of a programming language or database PHP isn t even doctrinaire about working only with other open source software This independent but cooperative pragmatism should help PHP ride out the stormy seas that seem to lie ahead 03 557467 ch01 qxd 4 5 04 11 06 AM Page 17 p Chapter 1 Why PHP and MySQL 17 Strong user communities PHP is developed and supported in a collaborative fashion by a worldwide community of users Some animals such as the core developers are more equal than others but that s hard to argue with because they put in the most work had the best ideas and have managed to maintain civil relationships with the greatest number of other users The main advantage for most new users is technical support without charge without bound aries and without the runaround People on the mailing list are available 24 7 365 to answer your questions help debug your code and listen to your gripes The support is human
23. k IBM any hardware manufacturer NASA Amazon com Rockpointe Broadcasting Ernie Ball Corporation the Queen of England or the Mexican school system If your boss still needs to be convinced further ammunition is available at www opensource org and www fsf org The PHP license The freeness of open source and Free software is guaranteed by a gaggle of licensing schemes most famously the GPL Gnu General Public License or copyleft PHP used to be released under both the GPL and its own license with each user free to choose between them This has recently changed The program as a whole is now released under its own extremely laissez faire PHP license on the model of the BSD license whereas Zend as a standalone product is released under the Q Public License this clause applies only if you unbundle Zend from PHP and try to sell it You can read the fine print about the relevant licenses at these Web sites www php net license www mysql com doc en GPL_license html www troll no qpl annotated html Most people get PHP or MySQL via download but you may have paid for it as part of a Linux distribution a technical book or some other product In that case you may now be silently disputing our assertion that PHP costs nothing Here s the twist Although you can t require a fee for most open source software you can charge for delivering that software in a more con venient format such as by putting it on a disk and shipping the
24. l suck up all assigned variables marked by dollar signs and try to plug them into later PHP commands in this case the echo function If everything goes smoothly the preprocessor will eventually return a normal HTML page to the client s browser as shown in Figure 1 1 03 557467 ch01 qxd 4 5 04 11 06 AM Page 10 F 10 Part PHP The Basics Example com greeting Mozilla Build ID 2002051006 BEE a Eile Edit View Go Bookmarks Tools Window Help Debug QA Q 6 Q amp http localhost sent_code ch1 greeting ph Search ss i O p u greeting php o Hil Hello Ms Park We know who you are Your first name is Joyce You are visiting our site at 2002 07 29 00 52 42 Here is a link to your account management page Joyce s account management page Document Done 0 82 secs P Figure 1 1 A result of preprocessed PHP If you peek at the source code from the client browser select Source or Page Source from the View menu or right click if you re using the AOL browser it will look like this lt HEAD gt lt TITLE gt Example com greeting lt TITLE gt lt HEAD gt lt BODY gt lt P gt Hello Ms Park We know who you are Your first name is Joyce lt P gt lt P gt You are visiting our site at 2002 04 21 19 34 24 lt P gt lt P gt Here is a link to your account management page lt A HREF http www example com accounts JoycePark gt Joyce s account management page lt A gt lt P gt l
25. me By early 1995 TcX had a 1 0 version of this new product ready They gave it the moniker MySQL and later that year released it under a combination open source and commercial licensing scheme that allowed continued develop ment of the product while providing a revenue stream for MySQL AB the company that evolved from TcX Over the past ten years MySQL has truly developed into a world class product MySQL now competes with even the most feature rich commercial database applications such as Oracle and Informix Additions in the 4 x series have included much requested features such as transactions and foreign key support All this has made MySQL the world s most used open source database Reasons to Love PHP and MySQL There are ever so many reasons to love PHP and MySQL Let us count a few Cost PHP costs you nothing Zip zilch nada not one red cent Nothing up front nothing over the lifetime of the application nothing when it s over Did we mention that the Apache PHP MySQL combo runs great on cheap low end hardware that you couldn t even think about for IIS ASP SQL Server MySQL is a slightly different animal in its licensing terms Before you groan at the concept of actually using commercial software consider that although MySQL is open source licensed for many uses it is not and has never been primarily community developed software MySQL AB is a commercial entity with necessarily commercial interests Unlike typical open s
26. ns of OS 2 Amiga NeXT Newton Firefly Netscape BeOS Napster and a host of other once hot technolo gies know the pain of abandonment when a company goes belly up decides to stop support ing a technology or is sold to a buyer with a new agenda The open source model reduces the chances of an ugly emergency port in a couple of years and thus makes long term planning more realistic Many extensions PHP makes it easy to communicate with other programs and protocols The PHP develop ment team seems committed to providing maximum flexibility to the largest number of users Database connectivity is especially strong with native driver support for about 15 of the most popular databases plus ODBC In addition PHP supports a large number of major protocols such as POP3 IMAP and LDAP PHP4 added support for Java and distributed object architec tures COM and CORBA making n tier development a possibility for the first time PHP5 extends this support even further offering a fully incorporated GD graphics library and revamped XML support with DOM and simpleXML Most things that PHP does not support are ultimately attributable to closed source shops on the other end For instance Microsoft has not thus far been eager to cooperate with open source projects like PHP Potential users who complain about lack of native Mac OS 9 or NET support on the PHP mailing list are simply misinformed about where the fault lies Fast feature development Us
27. ose also new to Unix tend to feel that source code is about as useful as a third leg and most vastly prefer a nice convenient rpm But there are both prag matic and idealistic reasons for including folders full of pesky c and h files The most immediate pragmatic advantage is that you can compile your PHP installation with only the stuff you really need for any given situation This approach has performance and security advantages For instance you can put in hooks to the database s of your choice You can recompile as often as you want maybe when an Apache security release comes out or when you wish to support a new database application By compiling a custom application specifically suited to your system or any given snapshot of your system performance and stability are increased over their already respectable baseline What sets open source software apart from its competitors is not just price but control Plenty of consumer software is now given away under various conditions Careful scrutiny of the relevant licenses however will generally reveal limits as to how the software can be used Maybe you can run it at home but not at the office Perhaps you can load it on your laptop but you re in violation if you use it for business purposes Or most commonly you can use it for anything you want but forget about looking at the code much less changing it There are even community licenses that force you to donate your improvements to the
28. ource projects where developers often have regular full time and paying day jobs in addition to their freely given open source efforts the MySQL developers derive their primary income from the project There are still many circumstances in which MySQL can be used for free basically anything nonredistributive which covers most PHP based projects but if you make money developing solutions that use MySQL consider buying a license or a support contract It s still infinitely more reasonable than just about any software license you will ever pay for For purposes of comparison Table 1 1 shows some current retail figures for similar products in the United States All prices quoted are for a single processor public Web server with the most common matching database and development tool 0 means a no cost alternative is a common real world choice Table 1 1 Comparative Out of Pocket Costs ASP SQL ColdFusion Item Server MX SQL Server JSP Oracle PHP MySQL Development tool 0 2499 599 0 2000 0 249 Server 999 2298 0 35 000 0 RDBMS 4999 4999 15 000 0 220 E 03 557467 ch01 qxd 4 5 04 11 06 AM Page 7 F Chapter 1 Why PHP and MySQL 7 Open source software don t fear the cheaper But as the bard so pithily observed we are living in a material world where we ve internal ized maxims such as You get what you pay for There s no such thing as a free lunch and Things that sound too good to be true usu
29. r together aren t the panacea for every Web development problem but they present a lot of advantages PHP is built by Web developers for Web devel opers and supported by a large and enthusiastic community MySQL is a powerful standards compliant RDBMS that comes in at an extremely competitive price point even more so if you qualify for free use Both technologies are clear cut cases of the community banding together to address its own needs 03 557467 ch01 qxd 4 5 04 11 06 AM Page 18 G
30. t BODY gt lt HTML gt This code is exactly the same as if you were to write the HTML by hand So simple The HTML embeddedness of PHP has many helpful consequences PHP can quickly be added to code produced by WYSIWYG editors PHP lends itself to a division of labor between designers and scripters Every line of HTML does not need to be rewritten in a programming language PHP can reduce labor costs and increase efficiency due to its shallow learning curve and ease of use Perhaps the sweetest thing of all about embedded scripting languages is that they don t need to be compiled into binary code before they can be tested or used just write and run PHP is interpreted as are many newish computer languages although the Zend Engine does 03 557467 ch01 qxd 4 5 04 11 06 AM Page 11 p Chapter 1 Why PHP and MySQL 11 some behind the scenes precompiling into an intermediate form for greater speed with complex scripts But what if you happen to want compilation This can be desirable if you wish to distribute nonreversible binaries so others can use the code without being able to look at the source The Zend team now offers a precompiler Zend Encoder which will deliver the code in a non reversible intermediate representation as well as substantially speed up large complex PHP scripts Cross platform compatibility PHP and MySQL run native on every popular flavor of Unix including Mac OS X and Windows A huge percen
31. tage of the world s HTTP servers run on one of these two classes of operating systems PHP is compatible with the three leading Web servers Apache HTTP Server for Unix and Windows Microsoft Internet Information Server and Netscape Enterprise Server a k a iPlanet Server It also works with several lesser known servers including Alex Belits fhttpd Microsoft s Personal Web Server AOLServer and Omnicentrix s Omniserver application server Specific Web server compatibility with MySQL is not required since PHP will handle all the dirty work for you Table 1 2 shows a brief matrix of the possible OS Web server combinations Table 1 2 Operating Systems and Web Servers for PHP Variables UNIX Windows Flavors AIX A UX BSDI Digital UNIX Tru64 Windows 95 98 ME FreeBSD HP UX IRIX Linux Mac OS X Windows NT 2000 XP 2003 NetBSD OpenBSD SCO UnixWare Solaris SunOS Ultrix Xenix and more Web servers Apache fhttpd Netscape IIS PWS Netscape Apache Omni Now that PHP runs on Macintosh PHP is almost totally cross platform You can develop on almost any client OS using your favorite tools and then upload your PHP scripts to a server on almost any OS We ll discuss the development process in more detail in Chapter 3 Not tag based PHP is a real programming language ColdFusion by contrast is a bunch of predefined tags like HTML In PHP you can define functions to your heart s content just by typing a name an
32. ven neophyte users up and running quickly compared to other databases None of these will substitute for learning a little theory and employing good design practices but that subject is for another chapter HTML embeddedness PHP is embedded within HTML In other words PHP pages are ordinary HTML pages that escape into PHP mode only when necessary Here is an example lt HEAD gt lt TITLE gt Example com greeting lt TITLE gt lt HEAD gt lt BODY gt lt P gt Hello lt php We have now escaped into PHP mode Instead of static variables the next three lines could easily be database calls or even cookies or they could have been passed from a form firstname Joyce lastname Park title Ms echo title lastname OK we are going back to HTML now gt We know who you are Your first name is lt php echo firstname gt lt P gt lt P gt You are visiting our site at lt php echo date Y m d H i s gt lt P gt lt P gt Here is a link to your account management page lt A HREF http www example com accounts lt php echo firstname lastname gt gt lt php echo firstname gt s account management page lt A gt lt P gt lt BODY gt lt HTML gt When a client requests this page the Web server preprocesses it This means it goes through the page from top to bottom looking for sections of PHP which it will try to resolve For one thing the parser wil
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