1

Coms 463 Presentation

Programming with PHP

By: Seth Larson 2

A little bit about PHP.

PHP is an acronym for Hypertext Preprocessor. PHP is a general purpose server side scripting language that is used in web development. PHP supports many different databases like MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc. The best thing about PHP is it is open source software, so it is free. The link to the download is http://www.php.net. PHP files have file extension of ".php", ".php3", or ".phtml"

What do you need installed on your computer to use php?

To use PHP on your computer you need a server that supports PHP. Some servers that have the support are Apache(open source), IIS (Microsoft), and Oracle. The latest version of PHP can be found at http://www.php.net.

You can test if you already have support for PHP with the code on the right. Copy and paste it in notepad and then save to “C:\Inetpub\wwwroot” with the filename “phpinfo.php”. Type http://localhost/phpinfo in a browser don’t see anything your PHP is not working. The webpage will have all the information about your php configuration.

PHP scripts run on the server-side and are sent to the client in html form. The sever-side PHP script itself is embedded directly in the HTML. Likewise, you can embed HTML in the PHP script shown in below. The example prints “PHP rules” inside a HTML table. Echo is a print call in PHP.

PHP rules!

" ?>

If you view the page source you will see that the server sent all the code in html which looks like this.

PHP rules!

3

PHP Syntax All PHP scripting blocks begin with the tag “” and can be placed anywhere in html. PHP statements always end with a semicolon.

PHP variables Variables are easy to create with PHP. Just like in other high-level languages there are syntax rules. Some predefined variables as well as predefined functions exist like echo, $GLOBALS, and $POST, php is no different. Variables in PHP have to start with “$” followed by a name, example $variable_name.

The code just below shows how to concatenate variables and also how to use the “\” character to print the name of a variable. The first php block shows how to use the “\” character. The character needs to be directly in front of the variable name, this tells the server to print what directly follows and not to treat it as a variable.

"; echo $var_A; ?>

The following code shows how to use the (.) dot operator to concatenate the var_C and var_D variables. The code shows how to use a forward slash followed by a asterisk (“/*”) and then an asterisk followed by a forward slash (“*/”) for a block comment A single line comment syntax is double forward slashes (“//”) followed by the comment.

$var_C = "concatenation is done with a"; $var_D = "(.) dot operator"; echo $var_C.$var_D; ?> 4 PHP operators Operators, conditionals, and looping are the same as other high level languages  Arithmetic Operators +, -, /, *  Assignment Operators =, +=, -=, *=, /=, %=  Comparison Operators ==, !=, >, <, >=, <=  Logical Operators &&, ||, !

 If – else statement

if (condition) code to be executed else code to be executed

 While while { code to be executed; }

 Do-while do { code to be executed; } while (condition);

 For  Foreach

PHP and HTML Forms PHP automatically puts the HTML form elements in a global array labeled $_POST. Retrieving an element variable can be done by using the predefined variable $_POST[“element name”]. Just a note that if your form’s method is not “post” and instead is “get”, then the variables are available with the predefined variable $_GET [“element name”].

The following code is a html form with 3 textboxes, “Your Id”, “Your First Name “, and “Your Last Name.” There is a checkbox with the value “male” and one with the value “female”. The last element in the form is a submit button.

Your Id:  Your First name:  Your Last name: 
 Female:  5

Once the submit button is clicked the page is redirected to php_forms_next.php and the variables are added to the global array $POST. The code below prints the user entered variables from the form. $_POST[“element name”] is used to retrieve the form variables. Again I used the $POST variable because the previous page’s form method is “post”.

You said your Id number was: 
You said your First name was 
You said you Last name was  
You also said you are 
 
Your favorite color is 
  
PHP and Text Files To open a file use the fopen () function. The syntax for the file open function is “fopen (“filename to open”, “mode to open file”).”
The file can be opened in different modes o Read only (r) o Read / write (r+ or w+) o Write (w) o Append (a) o Read/Append (a+)  o Create (x)     6
PHP and MySQL database use: PHP supports many different databases like MySQL, Informix, Oracle, Sybase, Solid, PostgreSQL, Generic ODBC, etc. The code below works with “mydb,” a database created with MySQL. Mydb has 3 columns including “Id”, “First Name”, “Last Name.” MySQL is also open-source software. The sample code in this paper uses a MySQL database and PHP has predefined functions for use with MySQL. 
Read from a MySQL database. The code below connects to the MySQL database “mydb” and prints the first name column from each record. 
The first step is to connect to the database and the mysql_connect () function. The syntax for the function is mysql_connect("server address", "username", "password"). By default the database user name is “root.” Once connected to the MySQL server the database to use has to be selected. This is done using mysql_select_db ("database name", $db). $db being the label given to the mysql_connect () function. The next step is to send a query to the “mydb” database with mysql_query (). The syntax is mysql_query(“sql statement”). The result of the query is held at the label $result. The “first name” column of each record is printed. Last the connection to “mydb” is closed.  %s indicates that the variable in the second half of the expression (e.g., mysql_result($result,$i,"first")) should be treated as a string and printed.
  "; $i++; } mysql_close(); ?>  
The following sample code reads a database query one record at a time and displays the output in a HTMl table. The same steps are followed as above. First connect to MySQL, then select a database to use, send a SQL query and print the records inside a table. There are two columns in the table outputted. The first column holds the database column “id” and the second table column “First and Last Name” holds the database columns “First Name” and “Last Name”. In the while loop you see multiple $myrow[] variable calls. This is because $myrow holds the record from the database as an array. The use of myrow[0] gets the first variable in the array.
 7  \n"; echo "idFirst Name and Last Name\n"; while ($myrow = mysql_fetch_row($result)) { printf("%s %s %s\n", $myrow[0], $myrow[1], $myrow[2]); } echo "\n"; ?>  
Insert into a MySQL database. The sample code below is a HTML form that the user enters an id, first name, and last name into textboxes. The user entered variables are inserted into the “mydb” database when the submit button is clicked.
  
 
 Your Id:  Your First name:  Your Last name:  
 
 
  
To insert in a MySQL database you follow the same steps demonstrated twice in the sample codes above. Once connected the SQL query statement has to follow the syntax for a insert statement. The insert query below is $query = mysql_query(INSERT INTO employee VALUES ('$id','$first','$last'));. After an insert has been made the code prints each record in the database.
  
$db = mysql_connect("localhost", "root","seth"); mysql_select_db("mydb",$db); $query = "INSERT INTO employee VALUES ('$id','$first','$last')"; mysql_query($query); $result = mysql_query("SELECT * FROM employee",$db); echo "
\n"; 8 echo "\n"; while ($myrow = mysql_fetch_row($result)) { printf("\n", $myrow[0], $myrow[1], $myrow[2]); } echo "
idFirst Name and Last Name
%s %s %s
\n";
?>   9 Phpinfo.php example
Resources: http://www.w3schools.com http://www.php.net http://hotwired.lycos.com/webmonkey/programming/php/tutorials/tutorial4.html http://www.free2code.net/plugins/articles/read.php?id=84 10 Short answer.
1. What does php stand for? Answer: hypertext preprocessor
2. What character do all php variables start with? Answer: they all start with “$”
3. What is one server that supports php? Answer: Apache, IIS, oracle
4. There are two basic ways to print in Php, what are they? Answer: print and echo
5. Is php a server side or client side scripting language? Answer: server side
Multiple choice. 1. Once a php “post” form is submitted where are the element variables automatically created? A. $_POST B. $_GET
2. What will the output of this code be.  A. Hello World B. 1234 C. Hello World 1234
3. Php code is inside a wrapper that starts  A. true B. false
4. Can you use if- else and while statements in PHP? Answer: yes
5. Php operators, conditionals, and looping are the same as other high level languages. A. true B. false
Fill in the blank.
1. Free code that anyone can download and use is called ______code? Answer. Open source
2. __ is used to concatenate in php? 11 Answer: you use a period (“.”)
3. Php statements end with a ___? Answer: a semicolon (“;”)
4. Php statements be put ______in html code. Answer: anywhere
5. Php scripting blocks start with <____ and end with __>? Answer: ?php and ?