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Archive:PHP and MySQL Programming/Database Connectivity

2006-03-18T07:39:29Z

155.232.250.19:

[[Programming:PHP and MySQL|TOC]]

== Introduction ==

== Opening a Connection to a MySQL Database ==

== Creating a Query ==

== Retrieving data from a SELECT Query ==

== Closing a Database Connection ==

[[Programming:PHP and MySQL:File Handling|<< 3. File Handling]] | [[Programming:PHP and MySQL|TOC]] | [[Programming:PHP and MySQL:Session Handling|>> 6. Session Handling]]

Archive:PHP and MySQL Programming/Database Connectivity

2006-03-18T07:36:57Z

155.232.250.19:

Archive:PHP and MySQL Programming/Database Connectivity

2006-03-18T07:36:23Z

155.232.250.51:

[[Programming:PHP and MySQL|TOC]]

Introduction

Opening a Connection to a MySQL Database

Creating a Query

Retrieving data from a SELECT Query

Closing a Database Connection

Archive:PHP and MySQL Programming/Form Handling

2006-03-18T07:30:36Z

155.232.250.51:

[[Programming:PHP and MySQL|TOC]]

== Introduction ==

In order to get user input without using the command line, then you will use HTML forms. PHP has various functions and techniques for handling the input from HTML forms. In specific, we will use the special array variables $_GET[] and $_POST[].

== HTML Forms ==

Before we start using these special variables, lets have a look at how to set up the HTML forms to interact with PHP. Here is a simple example form :

<HTML>
<HEAD><TITLE>HTML Form Example</TITLE></HEAD>
<BODY>
<FORM method='POST' action='form_handler.php'>
username : <INPUT type='text' name='username'> <BR>
password : <INPUT type='password' name='password'> <BR>
<INPUT type='submit' value='GO'>
</FORM>
</BODY>
</HTML>

The above example sets up a form with a `method` and an `action` attribute. The `method` defines how the data from the form is to be transferred to the page defined by `action`. The `method` can either be GET or POST. If GET is used, then all the form elements will be appended to the url of the target page (`action`), in this format : target?attrib1=val1&attrib2=val2&attrib3=val3 etc... These attributes are easily accessed in PHP by using the $_GET[] array variable;

If POST is used, then the data will be put into a special server variable, and accessed in PHP by using the $_POST[] array variable;

Note that in the HTML code, the `name` attribute of the INPUT tags are used as the reference strings in the $_GET and $_POST arrays, thus it is very important to always use unique values for the `name` attribute.

== GET ==

To retrieve GET variables in the address url, we use the following method :

form_handler.php :
<?
$username = $_GET['username'];
$password = $_GET['password'];
print "Username : $username \n Password : $password \n";
?>

Please note that GET is not good to use for this example, because you will generally not want username and password details being displayed in the URL. Rather use POST for login details and authentication.

== POST ==

To retrieve POST variables, we use the following method :

form_handler.php :
<?
$username = $_POST['username'];
$password = $_POST['username'];
print "Username : $username \n Password : $password \n";
?>

Note that when POST is used, the posted data is completely invisible to the user.

[[Programming:PHP and MySQL:Command Line Programming|<< 6. Command Line Programming]] | [[Programming:PHP and MySQL|TOC]]

Archive:PHP and MySQL Programming/Form Handling

2006-03-18T07:30:12Z

155.232.250.51:

[[Programming:PHP and MySQL|TOC]]

== Introduction ==

In order to get user input without using the command line, then you will use HTML forms. PHP has various functions and techniques for handling the input from HTML forms. In specific, we will use the special array variables $_GET[] and $_POST[].

== HTML Forms ==

Before we start using these special variables, lets have a look at how to set up the HTML forms to interact with PHP. Here is a simple example form :

<HTML>
<HEAD><TITLE>HTML Form Example</TITLE></HEAD>
<BODY>
<FORM method='POST' action='form_handler.php'>
username : <INPUT type='text' name='username'> <BR>
password : <INPUT type='password' name='password'> <BR>
<INPUT type='submit' value='GO'>
</FORM>
</BODY>
</HTML>

<FORM method='POST'>
username : <INPUT type='text' name='username'> <BR>
password : <INPUT type='password' name='password'> <BR>
<INPUT type='submit' value='GO'>
</FORM>

The above example sets up a form with a `method` and an `action` attribute. The `method` defines how the data from the form is to be transferred to the page defined by `action`. The `method` can either be GET or POST. If GET is used, then all the form elements will be appended to the url of the target page (`action`), in this format : target?attrib1=val1&attrib2=val2&attrib3=val3 etc... These attributes are easily accessed in PHP by using the $_GET[] array variable;

If POST is used, then the data will be put into a special server variable, and accessed in PHP by using the $_POST[] array variable;

Note that in the HTML code, the `name` attribute of the INPUT tags are used as the reference strings in the $_GET and $_POST arrays, thus it is very important to always use unique values for the `name` attribute.

== GET ==

To retrieve GET variables in the address url, we use the following method :

form_handler.php :
<?
$username = $_GET['username'];
$password = $_GET['password'];
print "Username : $username \n Password : $password \n";
?>

Please note that GET is not good to use for this example, because you will generally not want username and password details being displayed in the URL. Rather use POST for login details and authentication.

== POST ==

To retrieve POST variables, we use the following method :

form_handler.php :
<?
$username = $_POST['username'];
$password = $_POST['username'];
print "Username : $username \n Password : $password \n";
?>

Note that when POST is used, the posted data is completely invisible to the user.

[[Programming:PHP and MySQL:Command Line Programming|<< 6. Command Line Programming]] | [[Programming:PHP and MySQL|TOC]]

Archive:PHP and MySQL Programming/Form Handling

2006-03-18T07:29:47Z

155.232.250.35:

[[Programming:PHP and MySQL|TOC]]

== Introduction ==

In order to get user input without using the command line, then you will use HTML forms. PHP has various functions and techniques for handling the input from HTML forms. In specific, we will use the special array variables $_GET[] and $_POST[].

== HTML Forms ==

Before we start using these special variables, lets have a look at how to set up the HTML forms to interact with PHP. Here is a simple example form :

<HTML>
<HEAD><TITLE>HTML Form Example</TITLE></HEAD>
<BODY>
<FORM method='POST' action='form_handler.php'>
username : <INPUT type='text' name='username'> <BR>
password : <INPUT type='password' name='password'> <BR>
<INPUT type='submit' value='GO'>
</FORM>
</BODY>
</HTML>

<FORM method='POST'>
username : <INPUT type='text' name='username'> <BR>
password : <INPUT type='password' name='password'> <BR>
<INPUT type='submit' value='GO'>
</FORM>

The above example sets up a form with a `method` and an `action` attribute. The `method` defines how the data from the form is to be transferred to the page defined by `action`. The `method` can either be GET or POST. If GET is used, then all the form elements will be appended to the url of the target page (`action`), in this format : target?attrib1=val1&attrib2=val2&attrib3=val3 etc... These attributes are easily accessed in PHP by using the $_GET[] array variable;

If POST is used, then the data will be put into a special server variable, and accessed in PHP by using the $_POST[] array variable;

Note that in the HTML code, the `name` attribute of the INPUT tags are used as the reference strings in the $_GET and $_POST arrays, thus it is very important to always use unique values for the `name` attribute.

== GET ==

To retrieve GET variables in the address url, we use the following method :

form_handler.php :
<?
$username = $_GET['username'];
$password = $_GET['password'];
print "Username : $username \n Password : $password \n";
?>

Please note that GET is not good to use for this example, because you will generally not want username and password details being displayed in the URL. Rather use POST for login details and authentication.

== POST ==

To retrieve POST variables, we use the following method :

form_handler.php :
<?
$username = $_POST['username'];
$password = $_POST['username'];
print "Username : $username \n Password : $password \n";
?>

Note that when POST is used, the posted data is completely invisible to the user.

[[Programming:PHP and MySQL:Command Line Programming|<< 6. Command Line Programming]] | [[Programming:PHP and MySQL|TOC]]

Archive:PHP and MySQL Programming/Form Handling

2006-03-18T07:28:21Z

155.232.250.19:

[[Programming:PHP and MySQL|TOC]]

== Introduction ==

In order to get user input without using the command line, then you will use HTML forms. PHP has various functions and techniques for handling the input from HTML forms. In specific, we will use the special array variables $_GET[] and $_POST[].

== HTML Forms ==

Before we start using these special variables, lets have a look at how to set up the HTML forms to interact with PHP. Here is a simple example form :

<HTML>
<HEAD><TITLE>HTML Form Example</TITLE></HEAD>
<BODY>
<FORM method='POST' action='form_handler.php'>
username : <INPUT type='text' name='username'> <BR>
password : <INPUT type='password' name='password'> <BR>
<INPUT type='submit' value='GO'>
</FORM>
</BODY>
</HTML>

The above example sets up a form with a `method` and an `action` attribute. The `method` defines how the data from the form is to be transferred to the page defined by `action`. The `method` can either be GET or POST. If GET is used, then all the form elements will be appended to the url of the target page (`action`), in this format : target?attrib1=val1&attrib2=val2&attrib3=val3 etc... These attributes are easily accessed in PHP by using the $_GET[] array variable;

If POST is used, then the data will be put into a special server variable, and accessed in PHP by using the $_POST[] array variable;

Note that in the HTML code, the `name` attribute of the INPUT tags are used as the reference strings in the $_GET and $_POST arrays, thus it is very important to always use unique values for the `name` attribute.

== GET ==

To retrieve GET variables in the address url, we use the following method :

form_handler.php :
<?
$username = $_GET['username'];
$password = $_GET['password'];
print "Username : $username <BR> Password : $password \n";
?>

Please note that GET is not good to use for this example, because you will generally not want username and password details being displayed in the URL. Rather use POST for login details and authentication.

== POST ==

To retrieve POST variables, we use the following method :

form_handler.php :
<?
$username = $_POST['username'];
$password = $_POST['username'];
print "Username : $username <BR> Password : $password \n";
?>

Note that when POST is used, the posted data is completely invisible to the user.

[[Programming:PHP and MySQL:Command Line Programming|<< 6. Command Line Programming]] | [[Programming:PHP and MySQL|TOC]]

Archive:PHP and MySQL Programming/Form Handling

2006-03-18T07:10:01Z

155.232.250.51:

[[Programming:PHP and MySQL|TOC]]

== Introduction ==

In order to get user input without using Command Line Programming

== HTML Forms ==

== GET ==

== POST ==

[[Programming:PHP and MySQL:Command Line Programming|<< 6. Command Line Programming]] | [[Programming:PHP and MySQL|TOC]]

Archive:PHP and MySQL Programming/Session Handling

2006-03-18T07:09:12Z

155.232.250.19:

[[Programming:PHP and MySQL|TOC]]

== Introduction ==

HTML and PHP are "stateless" languages. Meaning that they are incapable of retaining a state between pages. To get around this serious limitation, we use Sessions. With sessions, session variables are stored in a file on the web server and so are acessible accross multiple pages.

== Starting a Session ==

Before we can start using session variables, we need to start a session. This needs to be done on every page that makes use of session variables. It is important to note that a session must be started BEFORE ANYTHING IS OUTPUTED. Here is the code to start a session :

<?
session_start();
?>

Please make sure that there are NO SPACES before the "<?" (php starting tag), as that will return errors!

It is worth noting, that the way in which the server distinguishes between multiple sessions being implemented on it simultaneously is by session ID's. When a unique session is created, it is assigned a Session ID, which the browser retains, and is used to let the we server know which session to use.

== Writing Session Variables ==

Once a session is created, variables may be stored in the $_SESSION[] array variable. Here is an example :

<?
session_start();
$_SESSION['user_name'] = "Administrator";
?>

== Retrieving Session Variables ==

Once a session is created, and variables are stored, they may be retrieved from the $_SESSION[] array. Here is an example :

<?
session_start();
if (isset($_SESSION['user_name'])){
$user_name = $_SESSION['user_name'];
print $user_name;
}
?>

The above example starts a session, then checks if the session variable 'user_name' has been created (with the isset() function), if it has, then it assigns its value to $user_name, and prints it to the screen.

== Destroying a Session ==

To destroy a session, we use the session_destroy() function. This is useful if we want to, for example, log a user off of a web-application. Thus we would use the following code :

logoff.php
<?
session_start();
session_destroy();
?>

Note that we first need to start the session before we destory it. This is because the session_destroy() function destroys the currently active session.

[[Programming:PHP and MySQL:Database Connectivity|<< 4. Database Connectivity]] | [[Programming:PHP and MySQL|TOC]] | [[Programming:PHP and MySQL:Command Line Programming|>> 6. Command Line Programming]]

Archive:PHP and MySQL Programming

2006-03-18T07:03:45Z

155.232.250.19:

== Table of Contents ==

'''PHP'''

1. [[Programming:PHP and MySQL:Introduction|Introduction to PHP]]

2. [[Programming:PHP and MySQL:PHP Syntax|Syntax Overview]]

3. [[Programming:PHP and MySQL:File Handling|File Handling]]

4. [[Programming:PHP and MySQL:Database Connectivity|Database Connectivity]]

5. [[Programming:PHP and MySQL:Session Handling|Session Handling]]

6. [[Programming:PHP and MySQL:Command Line Programming|Command Line Programming]]

7. [[Programming:PHP and MySQL:Form Handling|Form Handling]]

'''MySQL'''

1. [[Programming:PHP and MySQL:Introduction to MySQL|Introduction to MySQL]]

2. [[Programming:PHP and MySQL:Creating a Database|Creating a Database]]

3. [[Programming:PHP and MySQL:Creating a Table|Creating a Table]]