1. NMED 3850 A Advanced Online Design January 26, 2010 V. Mahadevan

2. Some PHP Fundamentals  PHP code is always written in a plain text file saved with the extension “.php”.  The web server will execute this file and return the results to the client.  Database connectivity and business logic are implemented in the PHP code.  Look and feel elements are typically implemented using Cascading Style Sheets (CSS).  CSS can be static or combined with PHP to dynamically set look and feel elements (more on this later).

3. PHP (cont.)  To start writing a PHP script, surround the code with: <?php // insert code here ?>  Whatever is written between the will be executed by the PHP interpreter running on the web server.  Comments are specified using // and are ignored by the PHP interpreter.

4. PHP (cont.)  Variables: an identifier for storing and accessing data items within a PHP script.  Variable are declared using the “$” sign and an identifier name: $var1; $var2;  Variables can be assigned values as follows: $var1 = 'hello'; $var2 = 'world'; $var3 = 1;  The keyword “echo” will print out the value of the variable.

5. PHP (cont.)  Remember that anything you print out (echo) using a PHP script will be rendered by the web browser, so it must be properly formatted HTML code. <?php echo ' '; echo ' Test Page '; echo ' '; $var1 = 'hello'; $var2 = 'world'; $var3 = 1; $var4 = 2; echo $var1. ' '. $var2; echo ' '; echo $var3 + $var4; echo ' '; ?>

6. PHP (cont.)  Variables can have different types:  Strings: sequences of text / characters  Numbers: integer, float  Boolean: TRUE, FALSE  PHP determines the type at runtime; there is no need to explicitly predefine the type.  $var1 = ‘hello’; // string type  $var2 = 1; // number (integer) type  $var3 = TRUE; // Boolean type

7. PHP (cont.)  PHP also has support for arrays: $array1 = array(1 => 2, 'hello' => 'world'); echo ' '; echo $array1[1]; echo ' '; echo $array1['hello']; $array1[5] = 'something'; echo ' '; echo $array1[5]; $array1[] = 'end of array'; echo ' '; echo $array1[6];

8. PHP (cont.)  If (expression) { // do something } else if (expression) { // do something else } else { // do something else } Expressions can be of the form: ($a == $b) // test equality ($a > $b) // test greater than

9. PHP (cont.)  While loops: while (expression) { // do something } do { // do something } while (expression)

10. PHP (cont.)  for (expression 1; expression 2; expression 3) { // do something } foreach ($array1 as $item) { // do something with $item }

11. PHP (cont.) <?php $hostname = 'localhost'; $username = ''; $password = ''; $connection = mysql_connect($hostname, $username, $password) or die ('Connection error!!!'); $database = 'peopledb'; mysql_select_db($database); $lastname = $_POST["last_name"]; print " Retrieved the following data from the MySQL Database based on last name = $lastname: "; $execute_statement = "SELECT * FROM person WHERE last_name='$lastname'"; $results = mysql_query($execute_statement) or die ('Error executing SQL statement!!!'); while($item = mysql_fetch_array($results)) {

12. PHP (cont.) print $item['last_name']; print " "; print $item['first_name']; print " "; print $item['age']; print " "; } ?>

13. Lab  Write 2 PHP scripts:  1. This script should generate a web page with a color background and text of various sizes / styles.  2. This script should read a database table and output the data using a HTML table.