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1
Server Technologies II
LAMP
Partly adapted from notes by Dayalarasu Vijayan
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Overview
◊ This set of notes are in these sections• LAMP Overview• PHP Introduction• PHP Basic Syntax• Installing PHP• PHP Configuration• Installing MySQL• PHPMyAdmin• MySQL Basics
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LAMP Overview
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The LAMP Stack◊ LAMP comes from
• L = Linux• A = Apache• M = MySQL• P = Perl/PHP/Python
◊ The LAMP stack is open source software that enables rapid development of web-based and database-based applications
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Installing LAMP
◊ Apache needs to be installed with some special entries in its configuration script and files
◊ Before we get to mySQL, we’ll need PHP to help administer mySQL
◊ Therefore assume that we’ll be using PHP• The P in LAMP can refer to any web-friendly
programming language
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Installing LAMP
◊ To install the LAMP stack you will need to install • Linux• Apache• MySQL• PHP or Perl or Python
◊ Linux is presumably already installed
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Installing LAMP
◊ There’s a sneaky way to install LAMP all at once on Windows, Linux, and other platforms• WAMP (as in Windows, Apache, MySQL,
PHP)• See also here for other options, e.g. MAMP
for Mac OS X, XAMPP for Linux/UNIX, etc.
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PHP Introduction
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PHP
◊ “PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML” • PHP is a recursive acronym (!) for
PHP: Hypertext Preprocessor• PHP is available from http://www.php.net• PHP is on version 5.3.5 as of 6 Jan 2011
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PHP Platforms◊ PHP can be used on all major operating
systems, including • Linux• Many Unix variants (e.g. HP-UX, Solaris and
OpenBSD)• Microsoft Windows• Mac OS X (should this be under Unix variants?)
• RISC OS
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PHP Binaries also exist for◊ AS/400 ◊ Mac OS X ◊ Novell NetWare ◊ OS/2 ◊ RISC OS ◊ SGI IRIX 6.5.x ◊ Solaris (SPARC, INTEL) ◊ Solaris OpenCSW packages
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PHP Web Servers◊ PHP has support for most web servers
• Apache• Microsoft IIS and PWS• Netscape and iPlanet servers• O’Reilly Website Pro server• Caudium, Xitami, OmniHTTPd, and others
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PHP database support
◊ PHP can communicate with almost any database management system• 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
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What can PHP do?
◊ PHP is mainly focused on server-side scripting, so you can do anything any other CGI program can do• Collect form data, generate dynamic page
content, send and receive cookies, etc.◊ But PHP can do much more
Summarized from http://www.php.net/manual/en/intro-whatcando.php
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What can PHP do?◊ Command line scripting
• You can make a PHP script and run it without any server or browser
◊ You only need the PHP parser• This type of usage is ideal for scripts regularly
executed using cron (on Unix or Linux) or Task Scheduler (on Windows)
• Scripts can also be used for simple text processing tasks
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What can PHP do?
◊ Writing desktop applications• PHP is probably not the best language to
create a desktop application with a graphical user interface, but it can be done
◊ Use PHP-GTK to write such programs • WinBinder is a (Windows only) alternative to
PHP-GTK
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What can PHP do?◊ Server-side scripting is the most traditional
and main target field for PHP◊ You need three things to make this work, a
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
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PHP output types
◊ A PHP server often outputs HTML, but it can also output• Images• PDF files• Flash movies• Any text, such as XHTML or other XML file
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PHP Basic Syntax
Summarized from http://www.php.net/manual/en/language.basic-syntax.php
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PHP example◊ <!DOCTYPE HTML PUBLIC "-//W3C//
DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Example</title> </head> <body> <?php echo "Hi, I'm a PHP script!"; ?> </body></html>
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PHP example
◊ The <?php and ?> are start and end processing instructions (a.k.a. opening and closing tags) • The PHP server interprets them, and sends
HTML to your web browser key concept!◊ PHP is done server-side, whereas
JavaScript is done on the client
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PHP is server interpreted
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%^$%^# semicolons!◊ Notice the commands end with a
semicolon, like most C-ish languages• PHP requires instructions to be terminated
with a semicolon at the end of each statement• The closing tag of a block of PHP code
automatically implies a semicolonYou do not need to have a semicolon terminating
the last line of a PHP block, it adds an extra whitespace if you do
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Short and long tags◊ You’ll see examples of PHP with start and
end processing tags like these• <? Stuff ?>
◊ These are called short tags, which by default are enabled, but should be avoided• short_open_tag = On
◊ Please use the officially correct long tags• <?php other stuff ?>
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Script tags
◊ Note: If you are embedding PHP within XML or XHTML you will need to use the <?php ?> tags to remain compliant with standards
◊ Other allowed opening and closing tags define the script language• <script language="php"> stuff </script>• FrontPage prefers this
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Accidental closing tags
◊ One aspect of PHP that you need to be careful of, is that ?> will drop you out of PHP code and into HTML even if it appears inside a // comment• This does not apply to /* blah */ multi-line
comments
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Comments<?php echo 'This is a test'; // This is a one-line c++ style comment /* This is a multi line comment yet another line of comment */ echo 'This is yet another test'; echo 'One Final Test'; # This is a one-line shell-style comment?>
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Comments
◊ PHP supports three different styles: 'C', 'C++' and Unix shell-style (Perl style)• // This is a one-line c++ style comment• /* This is a multi line comment
yet another line of comment */Don’t try to nest them!
• # This is a one-line shell-style commentOne-line comments go to EOL or end of php block
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Installing PHP
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Prerequisites for building PHP
◊ The following software is needed to build PHP• An ANSI C compiler • flex: Version 2.5.4 • bison: Version 1.28 (preferred), 1.35, or 1.75 • A web server • Any module specific components (such as
GD, PDF libs, etc.)
From http://www.php.net/manual/en/install.unix.php
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Installing PHP◊ Download the PHP source – follow the standard
procedure for installing a new software application
1. gzip -d httpd-2_0_NN.tar.gz 2. tar xvf httpd-2_0_NN.tar 3. gunzip php-NN.tar.gz 4. tar -xvf php-NN.tar 5. cd httpd-2_0_NN6. ./configure --enable-so
For multi-core processors add --enable-shared-core7. make 8. make install
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Installing PHP
◊ PHP uses an ini file – a kind of configuration file
◊ A configuration file is supplied in the source directory
◊ Copy the php.ini file to the appropriate directory
cp php.ini-dist /usr/local/lib/php.ini
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http.conf Modifications for PHP◊ Here’s the Apache connection
• The http.conf file needs to be modified so that Apache knows what to do when it encounters PHP
• Lines are added to the .conf file where similar lines are placed (have a look at the default http.conf file)
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http.conf Modifications for PHP
◊ Load the PHP 5 module LoadModule php5_module modules/libphp5.so ◊ Handle how file types are to be processedAddHandler application/x-httpd-php .php
AddHandler application/x-httpd-php-source .phps
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Stop and Restart Apache
◊ Once you have modified the http.conf file, in order to recognize the new setting you will need to stop and restart the server
◊ Use apachectl to accomplish this
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Testing PHP and Apache◊ One way to test to see if Apache is
correctly in place is to write some PHP and see if it runs as it should
◊ A quick and dirty test would be the canonical “Hello World” program in PHP
◊ A better test is to continue configuration of the LAMP stack so that you can see some significant functionality demonstrated
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PHP Configuration
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PHP configuration file
◊ There is a configuration file in PHP, php.ini• It’s in the path designated by the environment
variable PHPRC• Under Linux/Unix, its default location is /usr/local/lib or <install-path>/lib
• On Windows, it’s in the Windows directory◊ For the server versions of PHP, it’s read
only once when the web server is started
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Sample php.ini file; any text on a line after an unquoted semicolon (;) is ignored[php] ; section markers (text within square brackets) are also
ignored; Boolean values can be set to either:; true, on, yes; or false, off, no, noneregister_globals = offtrack_errors = yes
; you can enclose strings in double-quotesinclude_path = ".:/usr/local/lib/php"
; backslashes are treated the same as any other characterinclude_path = ".;c:\php\lib"
Notice that path statements do not include the actual file name
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php.ini file syntax
◊ Notice that the syntax in the PHP configuration file is different from within PHP scripts!• Comments start with a semicolon, and can
start mid-line• Section markers [anything between square
brackets] are also ignored• Most lines are directive = value format
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PHP configuration file
◊ The php.ini file has core directives, and may have extensions• The default php.ini file has well documented
dozens of options from which you can choose◊ The php.ini file must have that name!
• You can have multiple versions in different directories (hence the PATH importance)
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PHP directives
◊ Directive names are case sensitive ◊ The value assigned can be
• A string, a number• A PHP constant (e.g. E_ALL or M_PI)• An INI constant (On, Off, True, False, Yes, No
or None)• An expression (e.g. E_ALL & ~E_NOTICE)• A quoted string ("foo")
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User configuration file
◊ The php.ini file pertains to the entire PHP install
◊ Individual users may have a personal configuration file, “.user.ini”• user_ini.filename = ".user.ini“
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Shy PHP
◊ Your PHP install can hide itself from the outside world (e.g. for security reasons) by changing this default setting• expose_php = On
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Php.ini sections• Language Options • Resource Limits • Error handling and logging • Data Handling • Unicode settings • Paths and Directories • File Uploads (to allow or not)• Fopen wrappers (allows treatment of URLs as files)• Dynamic Extensions • Module Settings (incl. mySQL and cookie settings)
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Installing MySQL
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Install MySQL
◊ MySQL is an open source, enterprise class, database management system
◊ It is fully compliant with the SQL standard although, unlike products like Oracle that have opted for a rich base of features, MySQL has opted for simplicity
◊ All basic functionality is available – with perhaps a bit less “slickness” than other products
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Getting MySQL
◊ MySQL is available from http://www.mysql.com/• The MySQL Community Server is the free
version• The MySQL Enterprise Subscription is about
$600/year per server
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Download an Installable Image
◊ In the case of MySQL, building (compiling) the database management system does not result in major benefits unless the platform you are using is special• Downloads are available from here• The current version is 5.5.9
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MySQL Installation◊ In the case of windows, the installation
package comes in a zipped file• In the zip file is another named setup.exe• Double click (Windows) this file and an
installer will launch and walk you through installation
◊ Once the MySQL server is started, you can check to see if it is running using the command line client
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MySQL Installation
◊ When you install MySQL, an All Programs menu option is added to start the command line client
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PHPMyAdmin
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PHPMyAdmin
◊ One of the benefits of open source is that programmers are free to develop tools of their own choosing to benefit the community• One such tool is PHPMyAdmin, currently on
version 3.3.9.2• PHPMyAdmin is available from here• It’s compatible with PHP 5 and MySQL 5
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PHPMyAdmin
◊ We demonstrated earlier how to test MySQL using the command line to fire up a client so that we could enter some SQL• Although this might be a good way for those
who live and breathe SQL, some help might be a good thing to have
• PHPMyAdmin is one such tool that offers help in the management of MySQL
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PHPMyAdmin
◊ PHPMyAdmin is a GUI based interface for managing MySQL• It goes a little further because with it we can
carry out extensive data manipulation• It is written in PHP and its interface
mechanism is browser-based
PHP Beyond “Hello World”
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Our first PHP script: hello.php<html> <head> <title>PHP Test</title> </head> <body> <?php echo '<p>Hello World</p>'; ?> </body></html>
From http://us3.php.net/manual/en/tutorial.firstpage.php
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About Hello World
◊ Notice the file is hello.php, not hello.html◊ The file does not have to be executable,
just a plain boring text file
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phpinfo function
◊ Make a call to the phpinfo() function and you will see a lot of useful information about your system and setup such as available predefined variables, loaded PHP modules, and configuration settings• <?php phpinfo(); ?>
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$_SERVER
◊ $_SERVER is a reserved PHP variable that contains all web server information• <?phpecho $_SERVER['HTTP_USER_AGENT'];?>
◊ May get a response of• Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
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Superglobal variables
◊ More generally, $_SERVER is a superglobal variable• They are available throughout any script• The others are: $GLOBALS, $_GET,
$_POST, $_FILES, $_COOKIE, $_SESSION, $_REQUEST, and $_ENV
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Environment Variables
◊ Environment variables ($_ENV) are data from the PHP parser’s host system
◊ For example, we can find the host name• <?php if (isset($_ENV["HOSTNAME"])) $MachineName = $_ENV["HOSTNAME"]; else if (isset($_ENV["COMPUTERNAME"])) $MachineName = $_ENV["COMPUTERNAME"]; else $MachineName = ""; ?>
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Environment Variables
◊ This example determines if a particular variable name has been set (isset)• Then assigns the correct variable to the local
variable $MachineName◊ The if / elseif / else structure is
from C• Note that the if and elseif lines don’t have
semicolons
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Environment Variables
◊ We can get the user name like this• <?phpecho 'My username is ' .$_ENV["USER"] . '!';?>
◊ Or get cookie information from $_COOKIE• <?php
// Print an individual cookieecho $_COOKIE["TestCookie"];// Another way to debug/test is to view all cookiesprint_r($_COOKIE);?>
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Other PHP functions
◊ There are zillions (approximately) of functions predefined for use by PHP• Audio Formats Manipulation • Authentication Services • Calendar and Event Related Extensions • Command Line Specific Extensions • Compression and Archive Extensions • Credit Card Processing
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Other PHP functions
• Cryptography Extensions • Database Extensions • File System Related Extensions • Human Language and Character Encoding
Support • Image Processing and Generation • Mail Related Extensions • Mathematical Extensions
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Other PHP functions
• Non-Text MIME Output • Process Control Extensions • Connecting to Java, other Internet apps,
general networking (sockets, TCP, etc.)• Search Engine Extensions • Server Specific Extensions • Session Extensions
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Other PHP functions
• Text Processing • Variable and Type Related Extensions • Web Services • Windows Only Extensions • XML Manipulation
PHP Programming
Programming variables
◊ PHP does not require (or support) explicit type definition in variable declaration
◊ A variable's type is determined by the context in which the variable is used
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Programming variables
◊ PHP has four basic variable types• boolean (TRUE or FALSE, case-insensitive)• integer (between +/- 2.15E9 or 2^31)• float (floating-point number, aka double)
Precision varies with platform• string (1 character = 1 byte, hence no
Unicode direct support in PHP5) Often use single quotes ‘ ‘, with a backslash before a literal quote \’
or to get a literal backslash \\
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Programming variables
◊ PHP is very lax about variable typing◊ Declarations aren’t needed
• <?php$a_bool = TRUE; // a boolean; True also works$a_str = "foo"; // a string$an_int = 12; // an integerecho gettype($a_bool); // prints out: booleanecho gettype($a_str); // prints out: string
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Programming variables• // If this is an integer, increment it by fourif (is_int($an_int)) { $an_int += 4; }// If $bool is a string, print it out// (does not print out anything)if (is_string($a_bool)) { echo "String: $a_bool"; }?>
PHP arrays◊ An array in PHP is a series of comma-
separated key => value pairs • <?php$arr = array("somearray" => array(6 => 5, 13 => 9, "a" => 42));echo $arr["somearray"][6]; // yields 5echo $arr["somearray"][13]; // 9echo $arr["somearray"]["a"]; // 42?>
• Key must be an integer or string; value may be any type
Objects◊ PHP 5 is object oriented◊ ‘new’ instantiates an object from the class◊ <?phpclass foo { function do_foo() { echo "Doing foo."; } }$bar = new foo;$bar->do_foo();?>
Objects• <?phpclass MyClass { }class NotMyClass { }$a = new MyClass;var_dump($a instanceof MyClass);var_dump($a instanceof NotMyClass);?>
◊ Yields:bool(true) bool(false)
Resources
◊ A resource is a special variable, holding a reference to an external resource
◊ Resources are created and used by special functions (link is to index of them)• The function is_resource() can be used to
determine if a variable is a resource• get_resource_type() will return the type of
resource it is
Resources
◊ Relevant creation resources include• mysql_connect() (Link to MySQL database)• mysql_pconnect() (Persistent link to
MySQL)• mysql_db_query(), mysql_list_dbs(),
mysql_list_fields(), mysql_list_processes(), mysql_list_tables(), mysql_query(), mysql_unbuffered_query() (MySQL result)
Resources
• odbc_connect() (Link to ODBC database)• odbc_pconnect() (Persistent link to
ODBC database)• odbc_prepare() (ODBC result)
NULL variables
◊ NULL (or null) variables and values are allowed• <?php$var = NULL; ?>
◊ See also the functions is_null() and unset()◊ The is-exactly-equals comparison (===)
can also check a null or boolean variable
Timing processing◊ <?php
$v = NULL;$s = microtime(TRUE);for($i=0; $i<1000; $i++) { is_null($v); }print microtime(TRUE)-$s;print "<br>";$s = microtime(TRUE);for($i=0; $i<1000; $i++) { $v===NULL; }print microtime(TRUE)-$s;?>
◊ Results:0.0179820060729980.0005950927734375Using "===" is 30x quicker than is_null()
Variable empty or not?
◊ Compare empty(), is_null(), and !isset()◊ $var = "";empty($var) is trueis_null($var) is false!isset($var) is false.
Type juggling◊ <?php$foo = "0"; // $foo is string (ASCII 48)$foo += 2; // $foo is now an integer (2)$foo = $foo + 1.3; // $foo is now a float (3.3)$foo = 5 + "10 Little Piggies"; // $foo is integer (15)$foo = 5 + "10 Small Pigs"; // $foo is integer (15)?>
◊ Strings with a period, e, or E (e.g. 1e-3 or 23.4) are interpreted as float, otherwise the leading integer value is used
Variables
◊ Variables in PHP are represented by a dollar sign followed by the name of the variable• The variable name is case-sensitive
◊ A variable can be assigned by reference. • This means that the new variable "points to"
the original variable
Variables• Changes to the new variable affect the original, and
vice versa • Only named variables may be assigned by reference
◊ <?php$foo = 'Bob'; // Assign the value 'Bob' to $foo$bar = &$foo; // Reference $foo via $bar.$bar = "My name is $bar"; // Alter $bar...echo $bar;echo $foo; // $foo is altered too.?>
Predefined variables
◊ The superglobal variables are predefined, as are• $php_errormsg — The previous error message • $HTTP_RAW_POST_DATA — Raw POST data • $http_response_header — HTTP response headers • $argc — The number of arguments passed to script • $argv — Array of arguments passed to script
Detecting settings
◊ To detect user settings (video resolution, browser type, etc.) try this link(link removed)
Expressions
◊ Most logical comparison operators are allowed • < > >= <= != ==• === (identical, equal to and same type) • !== (not equal to or not same type).
◊ These can also be used on arrays
Ternary expressions
◊ <?php$first ? $second : $third?> • If the value of the first subexpression is
TRUE (non-zero), then the second subexpression is evaluated, and that is the result of the conditional expression. Otherwise, the third subexpression is evaluated, and that is the value.
Increment/decrement operators◊ ++$a Increments $a by one, then returns $a
◊ $a++ Returns $a, then increments $a by one
◊ --$a Decrements $a by one, then returns $a
◊ $a-- Returns $a, then decrements $a by one
Nesting assignments
◊ An assignment statement has a value of the value assigned, so it’s possible to nest them • <?php$a = ($b = 4) + 5; // $a is equal to 9 now, and $b has been set to 4.?>
Execution operator◊ PHP supports one execution operator:
backticks (``)• Not single-quotes(‘’)! • PHP will execute the contents of the backticks
as a shell command (e.g. bash, csh)• The output will be returned (i.e., it won't
simply be dumped to output; it can be assigned to a variable)
Execution operator
• Use of the backtick operator is identical to shell_exec()
◊ <?php$output = `ls -al`;echo "<pre>$output</pre>";?>
Error control operator
◊ The only error control operator is the at symbol, @
◊ Using it before an expression (variables, function and include() calls, constants, etc.) prevents error messages from appearing
Error message logging<?php session_start(); function error($error, $return=FALSE) { global $php_errormsg; if(isset($_SESSION['php_errors'])) { $_SESSION['php_errors'] = array(); } $_SESSION['php_errors'][] = $error; // Maybe use $php_errormsg if($return == TRUE) { $message = ""; foreach($_SESSION['php_errors'] as $php_error) { $messages .= $php_error."\n"; } return $messages; // Or you can use use $_SESSION['php_errors'] } }?>
Logical operators
◊ And $a and $b◊ Or $a or $b◊ Xor $a xor $b◊ Not ! $a◊ And $a && $b◊ Or $a || $b◊ Why are there two Ors and two Ands?
Logical operators
◊Cute example using ‘or’<?php//If the connection was success, "Connected to database" will be shown. //If the connection was failed, "Unable to connect" will be shown.(NOTE: The @ will hide error messages)@mysql_connect("localhost", "root", "password") or die("Unable to connect");echo "Connected to database";?>
String operations
◊ The period is critical for string operations, specifically concatenation• <?php$a = "Hello ";$b = $a . "World!"; // now $b contains "Hello World!"$a = "Hello ";$a .= "World!"; // now $a contains "Hello World!"?>
Control statements
◊ Many control structures are available• if else elseif/else if • while • do-while • for • foreach (nice for arrays)• switch (case statement)
Custom functions
◊ Functions can be user-defined, like in most languages
◊ <?phpfunction foo($arg_1, $arg_2, /* ..., */ $arg_n){ echo "Example function.\n"; return $retval;}?>
MySQL Basics
mySQL structure
◊ mySQL is running on a host, which may be different from the client host you’re using to access it
◊ mySQL contains databases• Each database typically includes many tables
A table has one or more fields (columns)Every data entry in a table is a record (row)
Connecting
◊ You connect to MySQL via a given host server and user name with the mysql command• shell> mysql -h host -u user -p• Enter password: ********
◊ You should get a welcome message• Welcome to the MySQL monitor. Commands end with ; or \g.• Your MySQL connection id is 25338 to server version:
5.1.39-standard• Type 'help;' or '\h' for help. Type '\c' to clear the
buffer.• mysql>
Connecting
◊ If you’re on the mySQL host already, can omit the host parameter• shell> mysql -u user –p
◊ If your mySQL configuration allows anonymous logins, then this will work• shell> mysql
Disconnecting
◊ To leave mySQL, QUIT (or \q) works• mysql> QUIT• Bye
◊ On UNIX/Linux, control D also exits
mySQL command principles
◊ A command normally consists of an SQL statement followed by a semicolon• There are some exceptions where a
semicolon may be omitted; QUIT is one◊ When you issue a command, mysql sends
it to the host server for execution and displays the results, then prints another mysql> prompt to indicate that it is ready for another command
mySQL command principles◊ mysql displays query output in tabular
form (rows and columns)• The first row contains labels for the columns• The rows following are the query results• Normally, column labels are the names of the
columns you fetch from database tables• If you're retrieving the value of an expression
rather than a table column, mysql labels the column using the expression itself
mySQL command principles
◊ mysql shows how many rows were returned and how long the query took to execute, which gives you a rough idea of server performance• These values are imprecise because they
represent wall clock time (not CPU or machine time), so they are affected by factors such as server load and network latency
Case sensitivity
◊ mySQL is case insensitive◊ These are all equivalent commands
• mysql> SELECT VERSION(), CURRENT_DATE;• mysql> select version(), current_date;• mysql> SeLeCt vErSiOn(), current_DATE;
mySQL examples
◊ mySQL• mysql> SELECT VERSION(), CURRENT_DATE;• +-----------------+--------------+• | VERSION() | CURRENT_DATE |• +-----------------+--------------+• | 5.1.2-alpha-log | 2005-10-11 |• +-----------------+--------------+• 1 row in set (0.01 sec)• mysql>
mySQL examples
◊ mySQL as a calculator for expressions• mysql> SELECT SIN(PI()/4), (4+1)*5;• +------------------+---------+• | SIN(PI()/4) | (4+1)*5 |• +------------------+---------+• | 0.70710678118655 | 25 |• +------------------+---------+• 1 row in set (0.02 sec)
Multiple commands◊ Many commands can appear on one line, separated by semicolons
• mysql> SELECT VERSION(); SELECT NOW();• +-----------------+• | VERSION() |• +-----------------+• | 5.1.2-alpha-log |• +-----------------+• 1 row in set (0.00 sec)• +---------------------+• | NOW() |• +---------------------+• | 2005-10-11 15:15:00 |• +---------------------+• 1 row in set (0.00 sec)
Waiting for semicolon◊ Commands can span multiple lines, since
mySQL won’t do anything until after a semicolon• mysql> SELECT• -> USER()• -> ,• -> CURRENT_DATE;• +---------------+--------------+• | USER() | CURRENT_DATE |• +---------------+--------------+• | jon@localhost | 2005-10-11 |• +---------------+--------------+
Oh, nevermind!
◊ To cancel a partial command, add \c in it• mysql> SELECT• -> USER()• -> \c• mysql>
◊ If \c is inside a text string, it will not cancel the command• ‘this is a string with \c in it’
Text strings
◊ You can write strings surrounded by either “'” or “"” characters (for example, 'hello' or "goodbye")
◊ mysql lets you enter strings that span multiple lines • mysql> SELECT * FROM my_table WHERE name = 'Johnson-
• '> Smith' AND age < 30;
Text strings
◊ When you see a '> or "> prompt, it means that you have entered a line containing a string that begins with a “'” or “"” quote character, but have not yet entered the matching quote that terminates the string. • This might mean you left out a closing quote
mysql> SELECT * FROM my_table WHERE name = 'Smith AND age < 30;
'>
Text strings
◊ Hence a prompt of '> or "> may mean that mysql expects to see the rest of an unterminated string
◊ How resolve this?• Often best to close the string, then cancel the
command'\c
• Why not just close the string?
SQL commands◊ Naturally most mySQL commands are directly
from SQL (or here or lots of books)• mysql> SHOW DATABASES;• +----------+• | Database |• +----------+• | mysql |• | test |• | tmp |• +----------+
Database permissions
◊ Check your privileges to use a database with the USE command• mysql> USE test• Database changed
◊ Notice the lack of semicolon; it’s optional for this command
◊ And USE must be the only command on the line
PHP and mySQL◊ The key PHP extension to connect it to
mySQL is the mysqli class• <?php $link = mysqli_connect( 'localhost', 'user', 'password', 'world'); /* default db */ if (!$link) { printf("Can't connect to MySQL Server. Errorcode: %s\n", mysqli_connect_error()); exit; }
PHP and mySQL
◊ mysqli_connect is an improved version of mysql_connect, for PHP5 and mySQL4.1 or higher
◊ Do not use mysql_pconnect; it doesn’t play nicely with LAMP
PHP and mySQL◊ /* Send a query to the server */ if ($result = mysqli_query($link, 'SELECT Name, Population FROM City ORDER BY Population DESC LIMIT 5')) { print("Very large cities are:\n"); /* Fetch the results of the query */ while( $row = mysqli_fetch_assoc($result) ){ printf("%s (%s)\n", $row['Name'], $row['Population']); } /* Destroy the result set and free the memory used for it */ mysqli_free_result($result); }
PHP and mySQL
◊ This example would produce output like• Very large cities are:
Mumbai (Bombay) (10500000)Seoul (9981619)São Paulo (9968485)Shanghai (9696300)Jakarta (9604900)
PHP and mySQL
◊ Close a mySQL connection like this• /* Close the connection */ mysqli_close($link); ?>
Prepared statements
◊ mySQL has two useful types of prepared statements• Bound parameter prepared statements • Bound result prepared statements
◊ Both help you create queries that are more secure, have better performance, and are more convenient to write
Bound parameter prepared statements
◊ Bound parameter prepared statements allow query templates to be created and then stored on the MySQL server• The body of the query is only sent to the MySQL
server once• When a query is needed, data to fill in the template is
sent to the MySQL server, and a complete query is formed and then executed
• To execute the query, only the data to fill in the template needs to be delivered to the MySQL server
Bound result prepared statements
◊ Bound result prepared statements allow the value of variables in a PHP script to be tied to the value of fields of data in a query result set• Create a query • Ask the MySQL server to prepare the query • Bind PHP variables to columns in the prepared query • Ask the MySQL server to execute the query • Request that a new row of data be loaded into the
bound variables
Prepared statement example• <?php $mysqli = new mysqli("localhost", "user", "password", "world"); if (mysqli_connect_errno()) { printf("Connect failed: %s\n", mysqli_connect_error()); exit(); }
Prepared statement example• /* prepare statement */ if ($stmt = $mysqli->prepare("SELECT Code, Name FROM Country WHERE Code LIKE ? LIMIT 5")) { $stmt->bind_param("s", $code); $code = "C%"; $stmt->execute();
Prepared statement example• /* bind variables to prepared statement */ $stmt->bind_result($col1, $col2); /* fetch values */ while ($stmt->fetch()) { printf("%s %s\n", $col1, $col2); } /* close statement */ $stmt->close();
Prepared statement example• /* close connection */ $mysqli->close(); ?>
◊ This example uses the object oriented format of commands instead of the procedural syntax• $mysqli = new mysqli("localhost", "user", "password", "world");
• $link = mysqli_connect( 'localhost', 'user', 'password', 'world');
OO versus procedural syntax
◊ $mysqli->connect_error vs mysqli_connect_error
◊ mysqli->close vs mysqli_close◊ mysqli->query vs mysqli_query◊ mysqli_stmt->bind_param vs mysqli_stmt_bind_param
Binding parameters
◊ In the binding of parameters (bind_param), each variable to be bound needs a character to define its typeBIND TYPE COLUMN TYPE i All INT types d DOUBLE and FLOAT b BLOBs s All other types
