What You Should Already Know

Before you continue you should have a basic understanding of the following:

• HTML/XHTML

• JavaScript

If you want to study these subjects first, find the tutorials on our Home page.
What is PHP?

• PHP stands for PHP: Hypertext Preprocessor
• 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
• PHP is free to download and use

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”

What is MySQL?

• MySQL is a database server
• MySQL is ideal for both small and large applications
• MySQL supports standard SQL
• MySQL compiles on a number of platforms
• MySQL is free to download and use

PHP + MySQL

• PHP combined with MySQL are cross-platform (you can develop in Windows and serve on a Unix platform)

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 find a web hosting plan with PHP and MySQL support

PHP (“Hypertext Preprocessor”) is a widely-used Open Source general-purpose scripting language that is especially suited for Web applications and website development, and can be embedded into HTML. Most of its syntax draws upon C, Java, and Perl, being very easy to learn. The main goal of the PHP language is to allow web developers to write dynamically generated web pages quickly, but due to its powerful flexibility, you can do much more with it.

What distinguishes PHP from something like client-side JavaScript is that the code is executed on the server. If you were to have a script similar to the above on your server, the client would receive the results of running that script, with no way of determining what the underlying code may be. You can even configure your web server to process all your HTML files with PHP, and then there’s really no way that users can tell what you have up your sleeve.

The best things in using PHP are that it is extremely simple for a newcomer, but offers many advanced features for a professional programmer.

If you require  professional Freelance PHP coding , please do not hesitate to contact me on 079 9111 855 or email info@mydeveloper.co.za

PHP – Strings

In the last lesson, PHP Echo, we used strings a bit, but didn’t talk about them in depth. Throughout your PHP career you will be using strings a great deal, so it is important to have a basic understanding of PHP strings.

PHP – String Creation

Before you can use a string you have to create it! A string can be used directly in a function or it can be stored in a variable. Below we create the exact same string twice: first storing it into a variable and in the second case we send the string directly to echo.

$my_string = "Tizag - Unlock your potential!";
echo "PHP - Unlock your potential!";
echo $my_string;

In the above example the first string will be stored into the variable $my_string, while the second string will be used in the echo and not be stored. Remember to save your strings into variables if you plan on using them more than once! Below is the output from our example code. They look identical just as we thought.

Display:

PHP – String Creation Single Quotes

Thus far we have created strings using double-quotes, but it is just as correct to create a string using single-quotes, otherwise known as apostrophes.

$my_string = 'Tizag - Unlock your potential!';
echo 'Tizag - Unlock your potential!';
echo $my_string;

If you want to use a single-quote within the string you have to escape the single-quote with a backslash \ . Like this: \’ !

echo 'FreelancePHP - It\'s Neat!';

PHP – String Creation Double-Quotes

We have used double-quotes and will continue to use them as the primary method for forming strings. Double-quotes allow for many special escaped characters to be used that you cannot do with a single-quote string. Once again, a backslash is used to escape a character.

$newline = "A newline is \n";
$return = "A carriage return is \r";
$tab = "A tab is \t";
$dollar = "A dollar sign is \$";
$doublequote = "A double-quote is \"";

Note: If you try to escape a character that doesn’t need to be, such as an apostrophe, then the backslash will show up when you output the string.

These escaped characters are not very useful for outputting to a web page because HTML ignore extra white space. A tab, newline, and carriage return are all examples of extra (ignorable) white space. However, when writing to a file that may be read by human eyes these escaped characters are a valuable tool!

PHP – String Creation Heredoc

The two methods above are the traditional way to create strings in most programming languages. PHP introduces a more robust string creation tool called heredoc that lets the programmer create multi-line strings without using quotations. However, creating a string using heredoc is more difficult and can lead to problems if you do not properly code your string! Here’s how to do it:

$my_string = <<<TEST
PHPMySQL.co.za
Webmaster Tutorials
Unlock your potential!
TEST;

echo $my_string;

There are a few very important things to remember when using heredoc.

• Use <<< and some identifier that you choose to begin the heredoc. In this example we chose TEST as our identifier.
• Repeat the identifier followed by a semicolon to end the heredoc string creation. In this example that was TEST;
• The closing sequence TEST; must occur on a line by itself and cannot be indented!

Another thing to note is that when you output this multi-line string to a web page, it will not span multiple lines because we did not have any <br /> tags contained inside our string! Here is the output made from the code above.

mysql_fetch_array: Why Use It?

Do you know what is returned when you used the mysql_query function to query a MySQL database? It isn’t something you can directly manipulate, that is for sure. Here is a sample SELECT query of a table we created in the MySQL Create Table lesson.

<?php
$result = mysql_query("SELECT * FROM example");
?>

The value that mysql_query returns and stores into $result is a special type of data, it is a MySQL Resource. Additional PHP functions are required to extract the data from this Resource.

A Row of Data

The mysql_fetch_array function takes a MySQL query resource as an argument ($result) and returns the first row of data returned by the mysql_query. Our table example basically looks like the table below.

example MySQL Table:

The first row of data in this table is “Timmy Mellowman” and “23″. When we fetch an array from our MySQL Resource $result it should have Timmy’s name and age in it.

Getting a Row of Data using mysql_fetch_array

mysql_fetch_array returns the first row in a MySQL Resource in the form of an associative array. The columns of the MySQL Result can be accessed by using the column names of the table. In our table example these are: name and age. Here is the code to print out the first MySQL Result row.

<?php
// Make a MySQL Connection
$query = "SELECT * FROM example"; 

$result = mysql_query($query) or die(mysql_error());

$row = mysql_fetch_array($result) or die(mysql_error());
echo $row['name']. " - ". $row['age'];
?>

Display:

This is just what we expected would happen! Now, the cool thing about mysql_fetch_array is that you can use it again on the same MySQL Resource to return the second, third, fourth and so on rows. You can keep doing this until the MySQL Resource has reached the end (which would be three times in our example).

Sounds like an awfully repetitive task. It would be nice if we could get all our results from a MySQL Resource in an easy to do script.

Fetch Array While Loop

As we have said, the mysql_fetch_array function returns an associative array, but it also returns FALSE if there are no more rows to return! Using a PHP While Loop we can use this information to our advantage.

If we place the statement “$row = mysql_fetch_array()” as our while loop’s conditional statement we will accomplish two things:

1. We will get a new row of MySQL information that we can print out each time the while loop checks its conditional statement.
2. When there are no more rows the function will return FALSE causing the while loop to stop!

Now that we know what we need to do and how to go about doing it, the code pretty much writes itself, so let’s move on to the next lesson. Just kidding! Here is the code that will print out all the rows of our MySQL Resource.

<?php
// Make a MySQL Connection
$query = "SELECT * FROM example"; 

$result = mysql_query($query) or die(mysql_error());

while($row = mysql_fetch_array($result)){
	echo $row['name']. " - ". $row['age'];
	echo "<br />";
}
?>

Display: