IT420: Database Management and Organization PHP 28 February 2006
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IT420: Database Management
and Organization
PHP
28 February 2006
Adina Crainiceanu
www.cs.usna.edu/~adina
Web Applications
Choose:
Operating system – Windows or Linux
Web server software – Apache
Database Management System – MySQL
Programming or scripting language – PHP
PHP
PHP: PHP Hypertext Preprocessor
Server-side scripting language
Browser never sees PHP - only the web
server sees it
PHP pages require a web server with PHP
support
Competitors: Perl, ASP.NET, JSP
PHP Strengths
High performance
Interface to many different database systems
Built-in libraries
Ease of learning and use
Object-oriented support
Portability
Open source
Free
Availability of support
PHP References
Online references
http://www.php.net
Online Tutorial
http://www.w3schools.com/php/default.asp
PHP and MySQL Web Development by
Luke Welling and Laura Thomson
MySQL/PHP Database Applications by
Brad Bulger, Jay Greenspan, David Wall
Example PHP Page – Server Side
Code as it appears on the Server side
<h2>Today's Headline:</h2>
<p>
<?php echo "World Peace Declared"; ?>
</p>
Begin and end PHP code to be interpreted by server PHP engine
Example PHP Page Processed –
Client Side
Code as it appears on the client browser side
<h2>Today's Headline:</h2>
<p>
"World Peace Declared“
</p>
Sokkit demo
Save .php files in C:\Sokkit\site
Run http://localhost/yourphpfile.php
Basic PHP Syntax
<html>
<body>
<?php echo "Hello World"; # this is a PHP test program ?>
</body>
</html>
HTML code
PHP tags
PHP statements
White space
Comments
PHP Tags
Preferred style:
<?php echo “Hello World”; ?>
Other styles:
<? echo “Hello World”; ?>
<SCRIPT LANGUAGE=‘php’> echo “Hello
World”; </SCRIPT>
<% echo “Hello World”; %>
PHP Statements
Tell PHP interpreter what to do
Example: echo, if, while …
<?php echo “Hello World"; ?>
Separated by semicolon
White space And Comments
White space is ignored
Comments:
/* multi-line
comment here */
// comment here
# comment here
# here is a comment ?> here is no comment
PHP Variables
Variable names start with $
$testvariable = 0;
Case sensitive
Variables do not have to be declared
Created when a value is assigned
Data types:
Integer
Float
String
Boolean
Array
Object
PHP Variables (cont.)
Variables type determined by content
$test1 = 0;
$test2 = 0.0;
$test2 = $test1;
$test2 = “Hello”;
//integer
//float
//integer
//Is this possible?
Variable variables
$varname = ‘test1’;
$$varname = 5; //result: $test1 = 5
PHP Constants
define(‘CONST1’, 5)
Constant Name – No $
$test2 = CONST1 * $test1;
Strings
String concatenation operator: . (dot)
$test1 = ‘I’m’;
Echo $test1.’ John’
Concatenate
Single quotes strings:
True literals
Double quotes strings – variables are
evaluated (interpolation):
Echo “$test1 John”
Lab Exercise
Start Sokkit
Create and run helloworld.php
Modify helloworld.php to use variables
Assign some text to two variables
Print the text obtained by concatenation
Arithmetic Operators
Operator
Description
Example
Result
+
Addition
x=2
x+2
4
-
Subtraction
x=2
5-x
3
*
Multiplication
x=4
x*5
20
/
Division
15/5
5/2
3
2.5
%
Modulus (division remainder)
5%2
10%8
10%2
1
2
0
++
Increment
x=5
x++
x=6
--
Decrement
x=5
x--
x=4
Assignment Operators
Operator
Example
Is The Same As
=
x=y
x=y
+=
x+=y
x=x+y
-=
x-=y
x=x-y
*=
x*=y
x=x*y
/=
x/=y
x=x/y
%=
x%=y
x=x%y
Comparison Operators
Operator
Description
Example
==
is equal to
5==8 returns false
!=
is not equal
5!=8 returns true
<>
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 to
5<=8 returns true
Logical Operators
Operator
Description
Example
&&
and
||
or
x=6 y=3
(x==5 || y==5) returns false
!
not
x=6 y=3
!(x==y) returns true
x=6 y=3
(x < 10 && y > 1) returns true
Control Statements
If (condition) {do something}
else { do something else}
Switch(variable) {
case value1: someCode2; break;
case value2: someCode2; break;
…
default: someCode; break;
}
Control Statements (cont)
while(condition){ do something}
do {something} while (condition)
for(init; condition; increment){something}
foreach(array as value){something}
Used for arrays
Arrays
$numbers = array(‘one’, ‘two’, ‘three’);
$arr[0] == ‘one’ is true
foreach($numbers as $current){
echo “Current element is $current”;
}
Lab Exercise
Create an array containing the following values:
(1900, 2000, 2004, 2005 ).
Use the array in a “foreach” loop to test if the
value is a leap year.
If it is a leap year print “XXXX is a leap year”
Else print “XXXX is not a leap year”
A year is a leap year if it is divisible by 4. If the
year is also divisible by 100 then it is NOT a leap
year unless it also divisible by 400. Thus, 1900
is not a leap year (divisible by 100 but not 400)
while 2000 is a leap year (divisible by 400).
Form Processing
Browser
Web Server
User enters
information into
the form then
“Submits” the
form
• Server receives form.
• The form’s action is the
name of the PHP script
• PHP engine parser
decodes the form contents
and variables then
processes the script
User sees the
results.
Results sent back to the
browser. Connection closes.
Input Form
<html>
<body>
<form action=“name_age.php" method="POST">
Enter your name: <input type="text" name="name" />
Enter your age: <input type="text" name="age" />
<input type="submit" />
</form>
</body>
</html>
Accessing the Form Variables
name_age.php needs to know the values
of the input fields
$age
//short style
Requires ‘register_globals’
$_POST[‘age’]
//medium style
$_GET[‘age’] if method is GET
$_REQUEST[‘age’]
$HTTP_POST_VARS[‘age’] //long style
name_age.php – Called on Submit
<html>
<body>
Welcome <?php echo $_POST[‘name’]; ?>.<br />
You are <?php echo $_POST[‘age’]; ?> years old!
</body>
</html>
Sample output:
Welcome John.
You are 28 years old!
