PHP - Web Development

What is PHP?
 PHP stands for PHP: Hypertext Preprocessor
 PHP is a server-side scripting languagePHP scripts are
executed on the server.
 PHP supports many databases (MySQL, Informix, Oracle,
Sybase, Solid, PostgreSQL, Generic ODBC, etc.)
 PHP is an open source software (OSS)
1

Why PHP?
 PHP runs on different platforms (Windows, Linux, Unix, etc.)
 PHP is compatible with almost all servers used today (Apache, IIS,
etc.)
 PHP is FREE to download from the official PHP resource:
www.php.net
 PHP is easy to learn
2

Where to Start?
 Install an Apache server on a Windows or Linux machine
 Install PHP on a Windows or Linux machine
 Install MySQL on a Windows or Linux machine
3

 Download PHP for free here: http://www.php.net/downloads.php
 Download MySQL for free here:
http://www.mysql.com/downloads/index.html
 Download Apache for free here: http://httpd.apache.org/download.cgi
4

Basic PHP Syntax
 A PHP scripting block always
 starts with <?php and
 ends with ?>
 Example
<?php
…….….
………..
?>
5

What is a PHP File?
 A PHP file normally contains
 HTML tags, just like an HTML file
 some PHP scripting code
6

Combining HTML and PHP
<html>
<head>
<title>A PHP script including HTML</title>
</head>
<body>
<b>
"hello world- HTML";
<?php
echo "hello world-PHP";
?>
</b>
</body>
</html>7

Comments in PHP
 In PHP, we use
// or # to make a single-line comment
/* and */ to make a large comment block.
8

Example
<html>
<body>
<?php
//This is a single-line comment
/*
This is
a comment
block
*/
?>
</body>
</html>
9

Variables in PHP
 Variables are used for storing a values, like text strings, numbers
or arrays.
 When a variable is set it can be used over and over again in your
script
 All variables in PHP start with a $ sign symbol.
 The correct way of setting a variable in PHP:
$var_name = value;
Eg: $name=“Sunil”;
10

Example
<?php
$txt = "Hello World!";
$number = 16;
echo $txt;
echo $number;
?>
11

Variable Naming Rules
A variable name must start with a
letter or an underscore "_"
A variable name can only contain
alpha-numeric characters and
underscores (a-Z, 0-9, and _ )
A variable name should not contain
spaces. If a variable name is more
than one word, it should be separated
with underscore ($my_string), or with
capitalization ($myString)
12

PHP String
 String variables are used for values that contains
character strings.
 Example 1:
<?php
$txt="Hello World";
echo $txt;
?>
The output of the code above will be:
Hello World
13

PHP String
 Example 2:
<?php
$txt1="Hello World";
$txt2="1234";
echo $txt1 . " " . $txt2;
?>
Hello World 1234
14

PHP String
 Example 2:
<?php
echo strlen("Hello world!");
?>
12
15

PHP Operators
 Arithmetic Operators
+ Addition
- Subtraction
* Multiplication
/ Division
% Modulus (division remainder)
++ Increment
-- Decrement
16

PHP Operators
Comparison Operators
== is equal to 5==8 returns false
!= is not equal 5!=8 returns true
> is greater than 5>8 returns false
< is less than 5<8 returns true
>= is greater than or equal to 5>=8 returns
false
<= is less than or equal to5<=8 returns true
17

Conditional Statements
If...Else Statement
 If you want to execute some code if a condition is true
and another code if a condition is false, use the if....else
statement.
 Syntax
if (condition)
code to be executed if condition is true;
else
code to be executed if condition is false;
18

Example 1:
<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
else
echo "Have a nice day!";
?>
</body>
</html>
19

Conditional StatementsExample 2:
<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
{
echo "Hello!<br />";
echo "See you on Monday!";
}
?>
</body>
</html>
20

 If you want to execute some code if one of several conditions are
true use the elseif statement
 Syntax
if (condition)
elseif (condition)
else
code to be executed if condition is false;
21

Conditional StatementsExample 3:
<html>
<body>
<?php
$d=date("D");
if ($d=="Fri")
elseif ($d=="Sun")
echo "Have a nice Sunday!";
else
echo "Have a nice day!";
?>
</body>
</html>
22

PHP Switch Statement
 If you want to select one of many blocks of code to be executed,
use the Switch statement.
 The switch statement is used to avoid long blocks of if..elseif..else
code.
23

PHP Switch StatementSyntax
switch (expression)
{
case label1:
code to be executed if expression = label1;
break;
case label2:
code to be executed if expression = label2;
break;
default:
code to be executed
if expression is different from both label1 and label2;
}24

PHP Switch StatementExample:
<html>
<body>
<?php
$x=2;
switch ($x)
{
case 1:
echo "Number 1";
break;
case 2:
echo "Number 2";
break;
case 3:
echo "Number 3";
break;
default:
echo "No number between 1 and 3";
}
?>
</body>
</html>
25

Exercise :
 Assign values to two variables. Use
comparison operators to test whether
the first value is
 The same as the second
 Less than the second
 Greater than the second
 Less than or equal to the second
 Print the result of each test to the
browser.
 Change the values assigned to your test
variables and run the script again.
26

PHP Arrays
What is an array?
 When working with PHP, sooner or later, you might want to
create many similar variables.
 Instead of having many similar variables, you can store the
data as elements in an array.
 Each element in the array has its own ID so that it can be
easily accessed.
27

PHP Arrays : Example 1
<?php
$names[0] = "Peter";
$names[1] = "Quagmire";
$names[2] = "Joe";
echo $names[1] . " and " . $names[2] .
" are ". $names[0] . "'s neighbors";
?>
The code above will output:
Quagmire and Joe are Peter's neighbors
28

PHP Arrays : Example 2
<?php
$names = array("Peter","Quagmire","Joe");
echo $names[1] . " and " . $names[2] .
" are ". $names[0] . "'s neighbors";
?>
The code above will output:
Quagmire and Joe are Peter's neighbors
29

Multidimensional Arrays
 In a multidimensional array,
 each element in the main array can also be an array.
 each element in the sub-array can be an array, and so on
30

Multidimensional Arrays
 In a multidimensional array,
 each element in the main array can also be an array.
 each element in the sub-array can be an array, and so on
31

PHP Looping
Looping statements in
PHP are used to execute
the same block of code a
specified number of
times.
32

PHP Looping
Looping statements in PHP are
used to execute the same block of
code a specified number of times.
In PHP we have the following
looping statements:
 while - loops
 do...while - loops
 for - loops
 foreach - loops33

The while Statement
 The while statement will execute a block of code if and
as long as a condition is true.
 Syntax
while (condition)
{
statement 1;
statement 2;
}
34

The while Statement
Example
.
.
.
$i=1;
while($i<=5)
{
echo "The number is " . $i . "<br />";
$i++;
}
.
.
.35

do...while Statement
The do...while statement will execute a
block of code at least once - it then will
repeat the loop as long as a condition
is true.
Syntax
do
{
code to be executed;
}
while (condition);
36

do...while Statement
 Example
.
.
$i=0;
do
{
$i++;
echo "The number is " . $i . "<br />";
}
while ($i<5);
.
.
37

The for Statement
 The for statement is used when you know how many
times you want to execute a statement or a list of
statements.
 Syntax
for (initialization; condition; increment)
{
}
38

The for Statement
 Example
.
.
for ($i=1; $i<=5; $i++)
{
echo "Hello World!<br />";
}
.
.
39

The foreach Statement
The foreach statement is used to loop
through arrays.
For every loop, the value of the current array
element is assigned to $value (and the array
pointer is moved by one) - so on the next
loop, you'll be looking at the next element.
Syntax
foreach (array as value)
{
}
40

The foreach Statement
Example
The following example demonstrates a loop
that will print the values of the given array:
<html>
<body>
<?php
$arr=array("one", "two", "three");
foreach ($arr as $value)
{
echo "Value: " . $value . "<br />";
}
?>
</body>
</html>
41

PHP Functions
 A function is a block of code that can be
executed whenever we need it.
 Creating PHP functions:
 All functions start with the word "function()"
 Name the function - It should be possible to
understand what the function does by its name.
The name can start with a letter or underscore
(not a number)
 Add a "{" - The function code starts after the
opening curly brace
 Insert the function code
 Add a "}" - The function is finished by a closing
curly brace
42

Example 1
A simple function that writes my name when it is called:
<html>
<body>
<?php
function writeMyName()
{
echo “Harvendra Pal Singh";
}
writeMyName();
?>
</body>
</html>
43

Example 2
<html>
<body>
<?php
function writeMyName()
{
echo "Kai Jim Refsnes";
}
echo "Hello world!<br />";
echo "My name is ";
writeMyName();
echo ".<br />That's right, ";
writeMyName();
echo " is my name.";
?>
</body>
</html>
44

Example 3
 The following example will write different first names,
<html>
<body>
<?php
function writeMyName($fname)
{
echo $fname . " .<br />";
}
echo "My name is ";
writeMyName(“Nimal");
echo "My name is ";
writeMyName(“Kamal");
echo "My name is ";
writeMyName(“Amal");
?>
</body>
</html>45

Example 4
 The following function has two parameters
<html>
<body>
<?php
function writeMyName($fname,$lname)
{
echo $fname . " Refsnes" . $lname . "<br />";
}
echo "My name is ";
writeMyName(“Nimal",“Amarasinghe");
echo "My name is ";
writeMyName(“Kamal",“Perera");
echo "My name is ";
writeMyName(“Amal",“Silva");
?>
</body>
</html>
46

PHP Functions - Return values
Functions can also be used to return values.
Example
<html>
<body>
<?php
function add($x,$y)
{
$total = $x + $y;
return $total;
}
echo "1 + 16 = " . add(1,16);
?>
</body>
</html>
47

PHP Forms
 The PHP $_GET and $_POST variables are used to
retrieve information from forms, like user input.
48

Example
 Welcome.htm
<html>
<body>
<form action="welcome.php" method="post">
Name: <input type="text" name="name" />
Age: <input type="text" name="age" />
<input type="submit" />
</form>
</body>
</html>
49

Example
 welcome.php
<html>
<body>
Welcome <?php echo $_POST["name"]; ?>.<br />
You are <?php echo $_POST["age"]; ?> years old.
</body>
</html>
50

PHP $_GET
 The $_GET variable is used to collect values from a form
with method="get".
 Information sent from a form with the GET method is
visible to everyone (it will be displayed in the browser's
address bar)
 It has limits on the amount of information to send (max.
100 characters).
51

Example
<form action="welcome.php"
method="get">
Name: <input type="text"
name="name" />
</form>
 Welcome.php
Welcome <?php echo $_GET["name"]; ?>.<br />
You are <?php echo $_GET["age"]; ?> years old!
52

Note:
 When using the $_GET variable all variable names and
values are displayed in the URL.
 So this method should not be used when sending
passwords or other sensitive information!
 The HTTP GET method is not suitable on large variable
values; the value cannot exceed 100 characters.
53

PHP $_POST
 The $_POST variable is used to collect values from a
form with method="post".
 Information sent from a form with the POST method is
invisible to others and has no limits on the amount of
information to send.
54

Example
<form action="welcome.php" method="post">
Enter your name: <input type="text" name="name"
/>
Enter your age: <input type="text" name="age" />
</form>
Welcome.php
Welcome <?php echo $_POST["name"]; ?>.<br />
You are <?php echo $_POST["age"]; ?> years old!55

Connecting to a MySQL
Database
 Before you can access and work with data in a
database, you must create a connection to the
database.
 In PHP, this is done with the mysql_connect() function.
 Syntax
mysql_connect(servername,username,password
);
 servername Optional. Specifies the server to connect to.
Default value is "localhost:3306"
 username Optional. Specifies the username to log in with.
Default value is the name of the user that owns
the server process
 password Optional. Specifies the password to log in with.
Default is ""
57

Example
 In the following example we store the
connection in a variable ($con). The "die"
part will be executed if the connection
fails:
<?php
$con = mysql_connect("localhost","peter","abc123");
if (!$con)
{
die('Could not connect: ' . mysql_error());
}
// some code
mysql_close($con);
?>
58

Create MySQLDatabase and
Tables
 To get PHP to execute a MySQL statement we must use
the mysql_query() function.
 This function is used to send a query or command to a
MySQL connection.
59

Example
 In the following example we create a database called "my_db":
<?php
if (!$con)
{
}
if (mysql_query("CREATE DATABASE my_db",$con))
{
echo "Database created";
}
else
{
echo "Error creating database: " . mysql_error();
}
mysql_close($con);
?>
60

Create a Table Example
if (!$con)
{
}
// Create table in my_db database
mysql_select_db("my_db", $con);
$sql = "CREATE TABLE person
(
FirstName varchar(15),
LastName varchar(15),
Age int
)";
mysql_query($sql,$con);
mysql_close($con);
61

Insert new records into a
database table
 Example
<?php
if (!$con)
{
}
mysql_query("INSERT INTO person (FirstName, LastName, Age)
VALUES ('Peter', 'Griffin', '35')");
mysql_query("INSERT INTO person (FirstName, LastName, Age)
VALUES ('Glenn', 'Quagmire', '33')");
mysql_close($con);
?>
62

Insert Data From a Form Into
a Database
 Example : insert.html
<html>
<body>
<form action="insert.php" method="post">
Firstname: <input type="text" name="firstname" />
Lastname: <input type="text" name="lastname" />
</form>
</body>
</html>
63

Insert Data From a Form Into
a Database Example : insert.php
<?php
if (!$con)
{
}
$sql="INSERT INTO person (FirstName, LastName, Age)
VALUES
('$_POST[firstname]','$_POST[lastname]','$_POST[age]')";
if (!mysql_query($sql,$con))
{
die('Error: ' . mysql_error());
}
echo "1 record added";
mysql_close($con)
?>
64

Thank you.....
Arena Animation Siliguri,
Niladri Karmakar
65
Siliguri

PHP - Web Development

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