Synapseindia php development tutorial

PPHHPP//MMyySSQQLL
DDeevveellooppmmeennttTTuuttoorriiaall
Introduction to Database

WWhhaatt iiss PPHHPP??
 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

WWhhaatt iiss PPHHPP ((ccoonntt’’dd))
 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 ddooeess PPHHPP ccooddee llooookk lliikkee??
 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
<?php
…
?>

CCoommmmeennttss iinn PPHHPP
 Standard C, C++, and shell comment symbols
// C++ and Java-style comment
# Shell-style comments
/* C-style comments
These can span multiple lines */

VVaarriiaabbllee uussaaggee
<?php
$foo = 25; // Numerical variable
$bar = “Hello”; // String variable
$foo = ($foo * 7); // Multiplies foo by 7
$bar = ($bar * 7); // Invalid expression
?>

EEcchhoo
 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

EEcchhoo eexxaammppllee
<?php
$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
?>
 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
“n” or “”)

AArriitthhmmeettiicc OOppeerraattiioonnss
<?php
$a=15;
$b=30;
$total=$a+$b;
Print $total;
Print “<p><h1>$total</h1>”;
// total is 45
?>
 $a - $b // subtraction
 $a * $b // multiplication
 $a / $b // division
 $a += 5 // $a = $a+5 Also works for *= and /=

CCoonnccaatteennaattiioonn
 Use a period to join strings into one.
<?php
$string1=“Hello”;
$string2=“PHP”;
$string3=$string1 . “ ” .
$string2;
Print $string3;
?>
Hello PHP

EEssccaappiinngg tthhee CChhaarraacctteerr
 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.
<?php
$heading=“”Computer Science””;
Print $heading;
?>
“Computer Science”

PPHHPP CCoonnttrrooll SSttrruuccttuurreess
 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;
}

IIff ...... EEllssee......
 If (condition)
{
Statements;
}
Else
{
Statement;
}
<?php
If($user==“John”)
{
Print “Hello John.”;
}
Else
{
Print “You are not John.”;
}
?>
No THEN in PHP

WWhhiillee LLooooppss
 While (condition)
{
Statements;
}
<?php
$count=0;
While($count<3)
{
Print “hello PHP. ”;
$count += 1;
// $count = $count + 1;
// or
// $count++;
?>
hello PHP. hello PHP. hello PHP.

DDaattee DDiissppllaayy
$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

MMoonntthh,, DDaayy && DDaattee FFoorrmmaatt
SSyymmbboollss
M Jan
F January
m 01
n 1
Day of Month d 01
Day of Month J 1
Day of Week l Monday
Day of Week D Mon

FFuunnccttiioonnss
 Functions MUST be defined before then can be
called
 Function headers are of the format
function functionName($arg_1, $arg_2, …, $arg_n)
 Note that no return type is specified
 Unlike variables, function names are not case
sensitive (foo(…) == Foo(…) == FoO(…))

FFuunnccttiioonnss eexxaammppllee
<?php
// 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
?>

IInncclluuddee FFiilleess
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:
<hr SIZE=11 NOSHADE WIDTH=“100%”>
<i>Copyright © 2008-2010 KSU </i></font><br>
<i>ALL RIGHTS RESERVED</i></font><br>
<i>URL: http://www.kent.edu</i></font><br>

PPHHPP -- FFoorrmmss
•AAcccceessss ttoo tthhee HHTTTTPP PPOOSSTT aanndd GGEETT ddaattaa iiss ssiimmppllee iinn PPHHPP
•TThhee gglloobbaall vvaarriiaabblleess $$__PPOOSSTT[[]] aanndd $$__GGEETT[[]] ccoonnttaaiinn tthhee
rreeqquueesstt ddaattaa
<?php
if ($_POST["submit"])
echo "<h2>You clicked Submit!</h2>";
else if ($_POST["cancel"])
echo "<h2>You clicked Cancel!</h2>";
?>
<form action="form.php" method="post">
<input type="submit" name="submit" value="Submit">
<input type="submit" name="cancel" value="Cancel">
</form>

WWHHYY PPHHPP –– SSeessssiioonnss ??
WWhheenneevveerr yyoouu wwaanntt ttoo ccrreeaattee aa wweebbssiittee tthhaatt aalllloowwss yyoouu ttoo ssttoorree aanndd ddiissppllaayy
iinnffoorrmmaattiioonn aabboouutt aa uusseerr,, ddeetteerrmmiinnee wwhhiicchh uusseerr ggrroouuppss aa ppeerrssoonn bbeelloonnggss ttoo,,
uuttiilliizzee ppeerrmmiissssiioonnss oonn yyoouurr wweebbssiittee oorr yyoouu jjuusstt wwaanntt ttoo ddoo ssoommeetthhiinngg ccooooll oonn
yyoouurr ssiittee,, PPHHPP''ss SSeessssiioonnss aarree vviittaall ttoo eeaacchh ooff tthheessee ffeeaattuurreess..
CCooookkiieess aarree aabboouutt 3300%% uunnrreelliiaabbllee rriigghhtt nnooww aanndd iitt''ss ggeettttiinngg wwoorrssee eevveerryy ddaayy..
MMoorree aanndd mmoorree wweebb bbrroowwsseerrss aarree ssttaarrttiinngg ttoo ccoommee wwiitthh sseeccuurriittyy aanndd pprriivvaaccyy
sseettttiinnggss aanndd ppeeooppllee bbrroowwssiinngg tthhee nneett tthheessee ddaayyss aarree ssttaarrttiinngg ttoo ffrroowwnn uuppoonn
CCooookkiieess bbeeccaauussee tthheeyy ssttoorree iinnffoorrmmaattiioonn oonn tthheeiirr llooccaall ccoommppuutteerr tthhaatt tthheeyy ddoo
nnoott wwaanntt ssttoorreedd tthheerree..
PPHHPP hhaass aa ggrreeaatt sseett ooff ffuunnccttiioonnss tthhaatt ccaann aacchhiieevvee tthhee ssaammee rreessuullttss ooff
CCooookkiieess aanndd mmoorree wwiitthhoouutt ssttoorriinngg iinnffoorrmmaattiioonn oonn tthhee uusseerr''ss ccoommppuutteerr.. PPHHPP
SSeessssiioonnss ssttoorree tthhee iinnffoorrmmaattiioonn oonn tthhee wweebb sseerrvveerr iinn aa llooccaattiioonn tthhaatt yyoouu cchhoossee
iinn ssppeecciiaall ffiilleess.. TThheessee ffiilleess aarree ccoonnnneecctteedd ttoo tthhee uusseerr''ss wweebb bbrroowwsseerr vviiaa tthhee
sseerrvveerr aanndd aa ssppeecciiaall IIDD ccaalllleedd aa ""SSeessssiioonn IIDD"".. TThhiiss iiss nneeaarrllyy 9999%% ffllaawwlleessss iinn
ooppeerraattiioonn aanndd iitt iiss vviirrttuuaallllyy iinnvviissiibbllee ttoo tthhee uusseerr..

PPHHPP -- SSeessssiioonnss •SSeessssiioonnss ssttoorree tthheeiirr iiddeennttiiffiieerr iinn aa ccooookkiiee iinn tthhee cclliieenntt’’ss bbrroowwsseerr
•EEvveerryy ppaaggee tthhaatt uusseess sseessssiioonn ddaattaa mmuusstt bbee pprroocceeeeddeedd bbyy tthhee
sseessssiioonn__ssttaarrtt(()) ffuunnccttiioonn
•SSeessssiioonn vvaarriiaabblleess aarree tthheenn sseett aanndd rreettrriieevveedd bbyy aacccceessssiinngg tthhee gglloobbaall
$$__SSEESSSSIIOONN[[]]
•SSaavvee iitt aass sseessssiioonn..pphhpp
<<??pphhpp
sseessssiioonn__ssttaarrtt(());;
iiff ((!!$$__SSEESSSSIIOONN[[""ccoouunntt""]]))
$$__SSEESSSSIIOONN[[""ccoouunntt""]] == 00;;
iiff (($$__GGEETT[[""ccoouunntt""]] ==== ""yyeess""))
$$__SSEESSSSIIOONN[[""ccoouunntt""]] == $$__SSEESSSSIIOONN[[""ccoouunntt""]] ++ 11;;
eecchhoo ""<<hh11>>""..$$__SSEESSSSIIOONN[[""ccoouunntt""]]..""<<//hh11>>"";;
??>>
<<aa hhrreeff==""sseessssiioonn..pphhpp??ccoouunntt==yyeess"">>CClliicckk hheerree ttoo ccoouunntt<<//aa>>

AAvvooiidd EErrrroorr PPHHPP -- SSeessssiioonnss
PHP Example: <?php
echo "Look at this nasty error below:<br />";
session_start();
?>
Error!
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
PHP Example: <?php
session_start();
echo "Look at this nasty error below:";
?>
Correct

DDeessttrrooyy PPHHPP -- SSeessssiioonnss
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():

DDeessttrrooyy PPHHPP -- SSeessssiioonnss
<?php
// start the session
session_start();
header("Cache-control: private"); //IE 6 Fix
$_SESSION = array();
session_destroy();
echo "<strong>Step 5 - Destroy This Session </strong><br />";
if($_SESSION['name']){
echo "The session is still active";
} else {
echo "Ok, the session is no longer active! <br />";
echo "<a href="page1.php"><< Go Back Step 1</a>";
}
?>

PPHHPP OOvveerrvviieeww
 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.

PPHHPP OOvveerrvviieeww ((ccoonntt..))
 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.

FFiirrsstt PPHHPP ssccrriipptt
 Save as sample.php:
<!– sample.php -->
<html><body>
<strong>Hello World!</strong><br />
<?php
echo “<h2>Hello, World</h2>”; ?>
<?php
$myvar = "Hello World";
echo $myvar;
?>
</body></html>

Example –– sshhooww ddaattaa iinn tthhee ttaabblleess
 Function: list all tables in your database.
Users can select one of tables, and show all
contents in this table.
 second.php
 showtable.php

sseeccoonndd..pphhpp
<html><head><title>MySQL Table Viewer</title></head><body>
<?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");

sseeccoonndd..pphhpp ((ccoonntt..))
$result = mysql_query("SHOW TABLES");
if (!$result) {
die("Query to show fields from table failed");
}
$num_row = mysql_num_rows($result);
echo "<h1>Choose one table:<h1>";
echo "<form action="showtable.php" method="POST">";
echo "<select name="table" size="1" Font size="+2">";
for($i=0; $i<$num_row; $i++) {
$tablename=mysql_fetch_row($result);
echo "<option value="{$tablename[0]}" >{$tablename[0]}</option>";
}
echo "</select>";
echo "<div><input type="submit" value="submit"></div>";
echo "</form>";
mysql_free_result($result);
mysql_close($conn);
?>
</body></html>

sshhoowwttaabbllee..pphhpp
<html><head>
<title>MySQL Table Viewer</title>
</head>
<body>
<?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());

sshhoowwttaabbllee..pphhpp ((ccoonntt..))
$fields_num = mysql_num_fields($result);
echo "<h1>Table: {$table}</h1>";
echo "<table border='1'><tr>";
// printing table headers
for($i=0; $i<$fields_num; $i++) {
$field = mysql_fetch_field($result);
echo "<td><b>{$field->name}</b></td>";
}
echo "</tr>n";
while($row = mysql_fetch_row($result)) {
echo "<tr>";
// $row is array... foreach( .. ) puts every element
// of $row to $cell variable
foreach($row as $cell)
echo "<td>$cell</td>";
echo "</tr>n";
}
mysql_free_result($result);
mysql_close($conn);
?>
</body></html>

FFuunnccttiioonnss CCoovveerreedd
 mysql_connect() mysql_select_db()
 include()
 mysql_query() mysql_num_rows()
 mysql_fetch_array()mysql_close()

Synapseindia php development tutorial

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