PHP/MySQL Tutorial
Introduction to Database
Goal of this tutorial
Not to teach everything about PHP, but provide the basic knowledge
Explain code of examples
Provide some useful references
PHP == ‘Hypertext Preprocessor’
Open-source, server-side scripting language
Used to generate dynamic web-pages
PHP scripts reside between reserved PHP tags
This allows the programmer to embed PHP scripts within HTML pages
What is PHP?
What is PHP (cont’d)
Interpreted language, scripts are parsed at run-time rather than compiled beforehand
Executed on the server-side
Source-code not visible by client
‘View Source’ in browsers does not display the PHP code
Various built-in functions allow for fast development
Compatible with many popular databases
What does PHP code look like?
Structurally similar to C/C++
Supports procedural and object-oriented paradigm (to some degree)
All PHP statements end with a semi-colon
Each PHP script must be enclosed in the reserved PHP tag
…
?>
Comments in PHP
Standard C, C++, and shell comment symbols
// C++ and Java-style comment

# Shell-style comments

/* C-style comments
These can span multiple lines */
Variables in PHP
PHP variables must begin with a “$” sign
Case-sensitive ($Foo != $foo != $fOo)
Global and locally-scoped variables
Global variables can be used anywhere
Local variables restricted to a function or class
Certain variable names reserved by PHP
Form variables ($_POST, $_GET)
Server variables ($_SERVER)
Etc.
Variable usage
$foo = 25; // Numerical variable
$bar = “Hello”; // String variable

$foo = ($foo * 7); // Multiplies foo by 7
$bar = ($bar * 7); // Invalid expression
?>
Echo
The PHP command ‘echo’ is used to output the parameters passed to it
The typical usage for this is to send data to the client’s web-browser
Syntax
void echo (string arg1 [, string argn...])
In practice, arguments are not passed in parentheses since echo is a language construct rather than an actual function
Echo example
Notice how echo ‘5x5=$foo’ outputs $foo rather than replacing it with 25
Strings in single quotes (‘ ’) are not interpreted or evaluated by PHP
This is true for both variables and character escape-sequences (such as “ ” or “\”)
$foo = 25; // Numerical variable
$bar = “Hello”; // String variable

echo $bar; // Outputs Hello
echo $foo,$bar; // Outputs 25Hello
echo “5x5=”,$foo; // Outputs 5x5=25
echo “5x5=$foo”; // Outputs 5x5=25
echo ‘5x5=$foo’; // Outputs 5x5=$foo
?>
Arithmetic Operations
$a - $b // subtraction
$a * $b // multiplication
$a / $b // division
$a += 5 // $a = $a+5 Also works for *= and /=
$a=15;
$b=30;
$total=$a+$b;
Print $total;
Print “

$total

”;
// total is 45
?>
Concatenation
Use a period to join strings into one.
$string1=“Hello”;
$string2=“PHP”;
$string3=$string1 . “ ” . $string2;
Print $string3;
?>
Hello PHP
Escaping the Character
If the string has a set of double quotation marks that must remain visible, use the [backslash] before the quotation marks to ignore and display them.
$heading=“”Computer Science””;
Print $heading;
?>
“Computer Science”
PHP Control Structures
Control Structures: Are the structures within a language that allow us to control the flow of execution through a program or script.
Grouped into conditional (branching) structures (e.g. if/else) and repetition structures (e.g. while loops).
Example if/else if/else statement:

if ($foo == 0) {
echo ‘The variable foo is equal to 0’;
}
else if (($foo > 0) && ($foo <= 5)) {
echo ‘The variable foo is between 1 and 5’;
}
else {
echo ‘The variable foo is equal to ‘.$foo;
}
If ... Else...
If (condition)
{
Statements;
}
Else
{
Statement;
}
If($user==“John”)
{
Print “Hello John.”;
}
Else
{
Print “You are not John.”;
}
?>
No THEN in PHP
While Loops
While (condition)
{
Statements;
}
$count=0;
While($count<3)
{
Print “hello PHP. ”;
$count += 1;
// $count = $count + 1;
// or
// $count++;
?>
hello PHP. hello PHP. hello PHP.
Date Display
$datedisplay=date(“yyyy/m/d”);
Print $datedisplay;
# If the date is April 1st, 2009
# It would display as 2009/4/1
2009/4/1
$datedisplay=date(“l, F m, Y”);
Print $datedisplay;
# If the date is April 1st, 2009
# Wednesday, April 1, 2009
Wednesday, April 1, 2009
Month, Day & Date Format Symbols
Functions
Functions MUST be defined before then can be called
Function headers are of the format

Note that no return type is specified
Unlike variables, function names are not case sensitive (foo(…) == Foo(…) == FoO(…))
function functionName($arg_1, $arg_2, …, $arg_n)
Functions example
// This is a function
function foo($arg_1, $arg_2)
{
$arg_2 = $arg_1 * $arg_2;
  return $arg_2;
}

$result_1 = foo(12, 3); // Store the function
echo $result_1; // Outputs 36
echo foo(12, 3); // Outputs 36
?>
Include Files
Include “opendb.php”;
Include “closedb.php”;
This inserts files; the code in files will be inserted into current code. This will provide useful and protective means once you connect to a database, as well as for other repeated functions.

Include (“footer.php”);
The file footer.php might look like:

---

Copyright © 2008-2010 KSU

ALL RIGHTS RESERVED

URL: http://www.kent.edu

PHP - Forms
Access to the HTTP POST and GET data is simple in PHP
The global variables $_POST[] and $_GET[] contain the request data
if ($_POST["submit"])
echo "

You clicked Submit!

";
else if ($_POST["cancel"])
echo "

You clicked Cancel!

";
?>

http://www.cs.kent.edu/~nruan/form.php
WHY PHP – Sessions ?
Whenever you want to create a website that allows you to store and display information about a user, determine which user groups a person belongs to, utilize permissions on your website or you just want to do something cool on your site, PHP`s Sessions are vital to each of these features.

Cookies are about 30% unreliable right now and it`s getting worse every day. More and more web browsers are starting to come with security and privacy settings and people browsing the net these days are starting to frown upon Cookies because they store information on their local computer that they do not want stored there.

PHP has a great set of functions that can achieve the same results of Cookies and more without storing information on the user`s computer. PHP Sessions store the information on the web server in a location that you chose in special files. These files are connected to the user`s web browser via the server and a special ID called a "Session ID". This is nearly 99% flawless in operation and it is virtually invisible to the user.
PHP - Sessions
Sessions store their identifier in a cookie in the client’s browser
Every page that uses session data must be proceeded by the session_start() function
Session variables are then set and retrieved by accessing the global $_SESSION[]

Save it as session.php
session_start();
if (!$_SESSION["count"])
$_SESSION["count"] = 0;
if ($_GET["count"] == "yes")
$_SESSION["count"] = $_SESSION["count"] + 1;
echo "

".$_SESSION["count"]."

";
?>
Click here to count
http://www.cs.kent.edu/~nruan/session.php
Avoid Error PHP - Sessions
PHP Example: echo "Look at this nasty error below:
";
session_start();
?>
Error!
PHP Example: session_start();
echo "Look at this nasty error below:";
?>
Correct

Warning: Cannot send session cookie - headers already sent by (output started at session_header_error/session_error.php:2) in session_header_error/session_error.php on line 3
Warning: Cannot send session cache limiter - headers already sent (output started at session_header_error/session_error.php:2) in session_header_error/session_error.php on line 3
Destroy PHP - Sessions
Destroying a Session
why it is necessary to destroy a session when the session will get destroyed when the user closes their browser. Well, imagine that you had a session registered called "access_granted" and you were using that to determine if the user was logged into your site based upon a username and password. Anytime you have a login feature, to make the users feel better, you should have a logout feature as well. That`s where this cool function called session_destroy() comes in handy. session_destroy() will completely demolish your session (no, the computer won`t blow up or self destruct) but it just deletes the session files and clears any trace of that session.
NOTE: If you are using the $_SESSION superglobal array, you must clear the array values first, then run session_destroy.
Here`s how we use session_destroy():
Destroy PHP - Sessions
// start the session
session_start();
header("Cache-control: private"); //IE 6 Fix
$_SESSION = array();
session_destroy();
echo "Step 5 - Destroy This Session
";
if($_SESSION[`name`]){
    echo "The session is still active";
} else {
    echo "Ok, the session is no longer active!
";
    echo "<< Go Back Step 1";
}
?>
http://www.cs.kent.edu/~nruan/session_destroy.php
PHP Overview
Easy learning
Syntax Perl- and C-like syntax. Relatively easy to learn.
Large function library
Embedded directly into HTML
Interpreted, no need to compile
Open Source server-side scripting language designed specifically for the web.
PHP Overview (cont.)
Conceived in 1994, now used on +10 million web sites.
Outputs not only HTML but can output XML, images (JPG & PNG), PDF files and even Flash movies all generated on the fly. Can write these files to the file system.
Supports a wide-range of databases (20+ODBC).
PHP also has support for talking to other services using protocols such as LDAP, IMAP, SNMP, NNTP, POP3, HTTP.
Save as sample.php:


Hello World!

echo “

Hello, World

”; ?>
$myvar = "Hello World";
echo $myvar;
?>

First PHP script
http://www.cs.kent.edu/~nruan/sample.php
Example – show data in the tables
Function: list all tables in your database. Users can select one of tables, and show all contents in this table.

second.php
showtable.php

http://www.cs.kent.edu/~nruan/second.php
second.php

// change the value of $dbuser and $dbpass to your username and password
$dbhost = `hercules.cs.kent.edu:3306`;
$dbuser = `nruan`;
$dbpass = ‘*****************’;
$dbname = $dbuser;
$table = `account`;
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if (!$conn) {
die(`Could not connect: ` . mysql_error());
}
if (!mysql_select_db($dbname))
die("Can`t select database");

second.php (cont.)
$result = mysql_query("SHOW TABLES");
if (!$result) {
die("Query to show fields from table failed");
}
$num_row = mysql_num_rows($result);
echo "

Choose one table:

";
echo "

";
echo "";
for($i=0; $i<$num_row; $i++) {
$tablename=mysql_fetch_row($result);
echo "{$tablename[0]}";
}
echo "";
echo "

";
echo "

";

mysql_free_result($result);
mysql_close($conn);
?>

showtable.php




$dbhost = `hercules.cs.kent.edu:3306`;
$dbuser = `nruan`;
$dbpass = ‘**********’;
$dbname = `nruan`;
$table = $_POST[“table”];
$conn = mysql_connect($dbhost, $dbuser, $dbpass);
if (!$conn)
die(`Could not connect: ` . mysql_error());
if (!mysql_select_db($dbname))
die("Can`t select database");
$result = mysql_query("SELECT * FROM {$table}");
if (!$result) die("Query to show fields from table failed!" . mysql_error());
showtable.php (cont.)
$fields_num = mysql_num_fields($result);
echo "

Table: {$table}

";
echo "";
// printing table headers
for($i=0; $i<$fields_num; $i++) {
$field = mysql_fetch_field($result);
echo "";
}
echo " ";
while($row = mysql_fetch_row($result)) {
echo "";
// $row is array... foreach( .. ) puts every element
// of $row to $cell variable
foreach($row as $cell)
echo "";
echo " ";
}
mysql_free_result($result);
mysql_close($conn);
?>

Functions Covered
mysql_connect() mysql_select_db()
include()
mysql_query() mysql_num_rows()
mysql_fetch_array() mysql_close()
History of PHP
PHP began in 1995 when Rasmus Lerdorf developed a Perl/CGI script toolset he called the Personal Home Page or PHP
PHP 2 released 1997 (PHP now stands for Hypertex Processor). Lerdorf developed it further, using C instead
PHP3 released in 1998 (50,000 users)
PHP4 released in 2000 (3.6 million domains). Considered debut of functional language and including Perl parsing, with other major features
PHP5.0.0 released July 13, 2004 (113 libraries>1,000 functions with extensive object-oriented programming)
PHP5.0.5 released Sept. 6, 2005 for maintenance and bug fixes
Recommended Texts for Learning PHP
Larry Ullman’s books from the Visual Quickpro series
PHP & MySQL for Dummies
Beginning PHP 5 and MySQL: From Novice to Professional by W. Jason Gilmore
(This is more advanced and dense than the others, but great to read once you’ve finished the easier books. One of the best definition/description of object oriented programming I’ve read)
PHP References
http://www.php.net <-- php home page
http://www.phpbuilder.com/
http://www.devshed.com/
http://www.phpmyadmin.net/
http://www.hotscripts.com/PHP/
http://geocities.com/stuprojects/ChatroomDescription.htm
http://www.academic.marist.edu/~kbhkj/chatroom/chatroom.htm
http://www.aus-etrade.com/Scripts/php.php
http://www.codeproject.com/asp/CDIChatSubmit.asp
http://www.php.net/downloads <-- php download page
http://www.php.net/manual/en/install.windows.php <-- php installation manual
http://php.resourceindex.com/ <-- PHP resources like sample programs, text book references, etc.
http://www.daniweb.com/techtalkforums/forum17.html  php forums
Create your own homepage
Login loki.cs.kent.edu
Create directory “public_html” in your home directory
Create two php files (second.php and showtable.php) we have discussed
Visit your homepage:
http://www.cs.kent.edu/~[username]/second.php
http://www.cs.kent.edu/~nruan/second.php
Gửi ý kiến

{$field->name}

$cell