PHP Introduction ( Fedora )

PHP Tutorial

By
Mr. V. Kishore Kumar MCA (2009-12)

Under the guidance of
Mr. S. Amirtharaj M.E., &
Mr. V. Neethidevan M.E.,

Contents
• Introduction to PHP

• Deploying PHP files

• PHP Functions to
interact with Mysql
06/07/12 MCA, Mepco Schlenk Engineering College, Sivakasi 2

Introduction to PHP

Contents

PHP
• PHP stands for PHP: Hypertext Preprocessor
• PHP is a powerful tool for making dynamic and
interactive Web pages.
• PHP is a server-side scripting language, like ASP
• PHP 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


What is a PHP file ?
• PHP files can contain text, HTML tags and
scripts
• PHP files are returned to the browser as plain
HTML
• PHP files have a file extension of ".php",
".php3", or ".phtml"


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 and runs efficiently on the
server side


Where to Start ?
To get access to a web server with PHP support,
you can:
• Install Apache (or IIS) on your own server,
install PHP, and MySQL
• Or install WAMP s/w for windows, LAMP for
Linux to easily develop web applications in
PHP
WAMP – Windows Apache Mysql & PHP
LAMP – Linux Apache Mysql & PHP


PHP Basics
• The PHP script is executed on the server, and the plain
HTML result is sent back to the browser
• A PHP script always starts with <?php and ends with ?>
• A PHP script can be placed anywhere in the document
• A PHP file normally contains HTML tags, and some PHP
scripting code
• Each code line in PHP must end with a semicolon.
• The semicolon is a separator and is used to distinguish
one set of instructions from another.


Sample file
<html>
<body>

<?php
echo "Hello World";
?>

</body>
</html>

Echo – output text in PHP.

There are two basic statements to output text with PHP: echo and print


Comments in PHP
In PHP, we use // to make a one-line comment or /* and */ to make a comment
block:

<html>
<body>

<?php
//This is a comment

/*
This is
a comment
block
*/
?>

</body>
</html>

PHP Variables
• Variables in PHP starts with a $ sign, followed by the
name of the variable
• The variable name must begin with a letter or the
underscore character
• A variable name can only contain alpha-numeric
characters and underscores (A-z, 0-9, and _ )
• A variable name should not contain spaces
• Variable names are case sensitive (y and Y are two
different variables)


Creating or Declaring PHP
Variables
• PHP has no command for declaring a variable

<?php
$txt="Hello World!";
$x=16;
?>

• PHP is a loosely typed language, automatically converts
the variable to the correct data type, depending on its
value
Note: When you assign a text value to a variable, put
quotes around the value


The Concatenation Operator
• The concatenation operator (.) is used to put two
string values together
<?php
$txt1="Hello World!";
$txt2="What a nice day!";
echo $txt1 . " " . $txt2;
?>

• The output of the code above will be:
Hello World! What a nice day!

Note : Operators, if..else, switch, loops & etc. are all same as of C syntax.


PHP Forms
• The most important thing to notice when dealing with HTML
forms and PHP is that any form element in an HTML page
will automatically be available to your PHP scripts
<html>
<body>
<form action="welcome.php" method="post">
Name: <input type="text" name="fname" />
Age: <input type="text" name="age" />
<input type="submit" />
</form>
</body>
</html>

• When a user fills out the form above and clicks on the submit
button, the form data is sent to a PHP file, called
"welcome.php":

“welcome.php”
<html>
<body>

Welcome <?php echo $_POST["fname"]; ?>!<br />
You are <?php echo $_POST["age"]; ?> years old.

</body>
</html>

Output
Welcome John!
You are 28 years old.

• Note: $_POST[“ “] specifies how the input value passed from another
form or page is get into new PHP scripting page


PHP $_GET Function

• Collect values in a form with method=“get”
• While using this method all values are displayed in
URL.

PHP $_POST Function
• Collect values in a form with method=“post”
• While using this method all values are not displayed
(invisible to others) in URL.


Deploying PHP files

Contents

Windows

• Install WAMP Web-Server Software and
deploy all your applications.
• Consider you have installed WAMP on “C:”
Drive. Then place all your .php files in the
following folder “C:wampwww”
• For further instructions please refer
http://www.tinkertech.net/tutor/wamp/index.html


Fedora

• Save your php files into “varwwwhtml”
folder. To place your files first we have to set
access permissions.

Follow the given steps below
• Open the Terminal.
• Log in as Super User. Type “su” command it
will ask for root password ( ask the technicians or
respective faculties).

Follow the steps (contd..)
• Next step is to change our current working
location.
• Type “cd ..” as many times until your present
working directory(can be found by using pwd
command) reaches “/”.
• Type cd var/www.
• Type “ls” it will list all the files & directories
present in that directory. We have to deploy
our php files under HTML.


Follow the steps (contd..)
 To set access permission to HTML folder use
chmod command
 type chmod 777 html.
 Now you have set the access permissions to
that folder. We can paste any files in under that
folder.

To display our PHP files in Browser,
• Before opening browser, ensure that apache
services is running or not.


• (In Browser) Type “localhost” in url and press
enter. If the apache services is running
correctly, it will shows fedora test page as
shown below.


• If it shows “Problems on page load error”
means, the apache services is not running.
open terminal (enter as super user (“su”))

– Type apchectl start – to start the apache server.
– Type apchectl stop – to stop the apache server.
(its not mandatory to stop).
• Note : create separate folders for your php
project under HTML folder
Ex: if folder name is “test”, then in url type as
localhost/test/yourphpfilename along with .php extension


PHP Functions to interact with
Mysql

Contents

MySql
• Most popular open-source database system
• We can create any number of databases under
particular databases we can create any number
of tables.
• Mysql GUI has been available in the market,
which allows us to add, edit, modify records,
tabels, databases easily


Steps to be followed in Fedora environment to
use Mysql
• Log in as super user in terminal by using “su”
command
• Then type mysql
• To lists all existing databases, type show
databases;
• To select a database, type use database_name;
• to lists all tables exists under that database, type
show tables;
• Note: Tables can be created only by selecting a
database first.


PHP Functions to access MySql
Before you can access data in a database,
you must create a connection to the database.
In PHP, this is done with the mysql_connect()
function.

mysql_connect(servername,username,passwo
rd);


Ex :-)
<?php
$con = mysql_connect("localhost","root","");
if (!$con)
{
die('Could not connect: ' . mysql_error());
}
// some code
mysql_close($con);
?>

• The connection will be closed automatically
when the script ends. To close the connection
before, use the mysql_close() function.
• mysql_select_db() -> Sets the current active
database on the server that's associated with
the specified link identifier. Every subsequent
call to mysql_query() will be made on the
active database.
• mysql_query() -> executes the INSERT
INTO statement, and a new record will be
added to the table.

• mysql_num_rows() -> Retrieves the number
of rows from a result set. This command is
only valid for statements like SELECT or
SHOW that return an actual result set. To
retrieve the number of rows affected by a
INSERT, UPDATE, REPLACE or DELETE
query, use mysql_affected_rows().
• mysql_fetch_array() -> return the first row
from the recordset as an array. Each call to
mysql_fetch_array() returns the next row in
the recordset.


Sample program to display data from database :
Ex:
mysql_connect("localhost","root","");
mysql_select_db("my_db");
$result = mysql_query("SELECT * FROM Persons");
while($row = mysql_fetch_array($result))
{
echo $row['FirstName'] . " " . $row['LastName'];
echo "<br />";
}

The while loop loops through all the records in the
recordset. To print the value of each row, we use the
PHP $row variable ($row['FirstName'] and
$row['LastName']).

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