1. DB Programming on the Web
COP4710 Database Systems
DB Programming on the Web

2. PHP + MySQL/MariaDB as a case study
Introduction
Programming Environment
Database Programming in the Web Era
Web Programming
PHP + MySQL/MariaDB
as a case study

3. Motivation
Here Comes Another Bubble:
Are you feeling “so behind the times”?
Closely relevant to your programming project!

4. What is Internet?

5. How does the web work?
Information is stored in documents called Web pages
index.html, index.php, etc.
Web pages are files on computers called Web servers
Apache, Nginx, IIS, etc.
Computers reading the Web pages are called Web clients
PCs, Laptops, Phones, Tablets, etc.
Web clients view the pages with a program called Web browsers
IE, Chrome, and Firefox, Opera, etc.

6. Key Concepts HTTP: Hyper-Text Transfer Protocol
The underlying protocol used by the World Wide Web
Defines how messages are formatted and transmitted
Defines actions Web servers and browsers should take in response to various commands
HTML: Hyper-Text Markup Language
Specific standard used for the World Wide Web
Can embed scripting languages (e.g. PHP, JavaScript)
Interpreted by web browser (client side)

7. Web Development Tools Client-side: Server-side:
HTML: Primary language for creating web pages (page structure)
CSS: How HTML elements are to be displayed (page style)
JavaScript: Client-side scripting language (browser behavior) ……
Server-side:
PHP: Server-side scripting language (server behavior)
SQL: Standard language for accessing and manipulating databases

8. LAMP (WAMP) Linux, Apache, MySQL and PHP Linux Apache (www.apache.org)
Solution stack of free, open source software
Linux
Unix-like open source computer operating system
Apache (
Open source web server, most popular in use
MySQL (
SQL relational database management system (RDBMS)
PHP (
Server side scripting language

9. XAMPP Free Web Server Solution Package
Cross-platform (Mac, Windows, Linux, Solaris):
Apache HTTP Server
MySQL/MariaDB databases, phpMyAdmin
PHP, Perl
FileZilla FTP Server ……
XAMPP Tutorial:

10. XAMPP
Install
Run
Test:

11. How to work? Put your helloworld.php file under xampp/htdocs folder
To test your program go to:
To check your MySQL database management system go to:
Create a Webserver on your computer with XAMPP
Create a Database and Table in phpMyAdmin

12. DB Programming SQL is a (very) high-level language Solutions
Not intended for general purpose computations
Solutions
Outside DBMS: use SQL together with general-purpose programming languages, e.g. PHP, etc.
Inside DBMS: augment SQL with constructs from general-purpose programming languages

13. Typical DB Programming Procedure
Connect to a DB Server
Specify what database you want to use
Create a string containing an SQL statement
Execute the statement
Extract the results into variables in the local programming language
Database Specific API
Designed and implemented by the DBMS vendor for a specific programming language

14. MySQL-PHP API - Connection
Mysql_connect opens a connection to the DBMS
It gets the DBMS and login information and returns a connection resource
The connection resource is used in future calls
mysqli_connect: new versions of PHP (>5.0)
Mysql_select_db selects the desired database
Mysql_close closes the connection at the end
It is automatically called at the end of the script
mysqli_close

15. Connection - Example MySQL-PHP API:: Connection example in PHP
$username = “USERNAME”;
$password = “PASSWORD”;
$host = “localhost”;
$dbname= “DatabaseName”;
$connect = mysql_connect($host, $username, $password);
mysql_select_db($dbname, $connect);
//Do Stuff with the DB Connection
mysql_close($connect);
PHP: Connect to a MySQL database

16. Executing SQL Statement
mysql_query(S, C)
Causes the SQL statement represented by S to be executed on connection C
query
mysql_query returns
a handle to the query result set
TRUE/FALSE for DELETE, UPDATE, and INSERT
We can detect DBMS initiated errors using mysql_error()

17. Executing SQL Statement - Example
$query = “SELECT * FROM Beer”;
$result = mysql_query($query, $connect);
$query = “INSERT INTO Beer (manf, beer) VALUES (“Miller”, “High Life”); ”
if (mysql_query($query, $connect)) {
echo “Insert Successful”;
} else {
echo “Insert Failed:”. mysql_error(); }

18. Fetching Tuples
When the SQL statement executed is a query, we need to fetch the tuples of the result
mysql_fetch_array(H)
gets the tuples from the result set H and
stores them in an associative array
Mysqli_fetch_array, Mysqli_fetch_assoc
mysql_free_result(H)
frees the result set
It is called automatically at the end of the script
Mysqli_free_result

19. Fetching Tuples: Example
$query = “SELECT * FROM Beer”;
$result = mysql_query($query, $connect);
While ($row = mysql_fetch_array($result)) {
$manf= $row[‘manf’];
$beer = $row[‘beer’];
echo “The beer”. $beer . “ is made by”. $manf; }
mysql_free_result($result);

20. Other PHP-MySQL Commands
mysql_num_rows(r)
Checks the Result handler to see how many rows were returned
mysql_affected_rows()
Useful on DELETE or UPDATE commands to see how many rows were changed
More functions at
Example: Create a Simple View Counter

21. Web Programming
Client Side Programming: Code that runs on the client side’s browser
HTML
Predominant markup language for web pages
Written in the form of HTML elements consisting of "tags" surrounded by angle brackets within the web page content
Javascript
often implemented as part of a web browser in order to provide enhanced user interfaces and dynamic websites

22. Web Programming
Client Side Programming: Code that runs on the client side’s browser
Applet and ActiveX
small application that performs one specific task and runs within a larger program
E.g. Java Applet running on web pages
AJAX (Asynchronous Javascript And XML)
To create interactive web applications
Using AJAX, web applications can send data and retrieve data from a server asynchronously (in the background)

23. Web Programming
Server Side Programming: Code that runs on the server side
CGI: standard protocol for server-client communication
PHP: open source
ASP.NET: Microsoft proprietary
JSP: JavaServer Pages
Python, e.g. Django web framework, open source
Ruby, e.g. Ruby on Rails, open source ……

24. HTML Hyper Text Markup Language Tags
.html & .htm format – both are correct
Interpreted by browser to show elements on the webpage
Can contain scripting languages (PHP, javascript, etc.)
Tags
Keywords surrounded by angle brackets <tag>
Tags come in pairs: opening and closing: <tag> </tag>
Elements come between these tag: <tag>element</tag>
<a href=“ here</a> = Click here

25. HTML Basic Tags <html> </html> <head> </head>
Contain all the elements in the page
<head> </head>
Contain header information such as title, meta data, stylesheets
<body> </body>
Contains elements that are to be shown on the webpage
<h1> … <h6> for headings
<img> image

26. HTML Basic Tags <table> table
<tr> table row
<td> table data
<form> : HTML forms are used to pass data to a server
text fields, checkboxes, radio-buttons, submit buttons and etc.
$_GET and $_POST methods

27. HTML Tag Attributes Each tag has attributes Example
Attributes provide additional information about the element
Should be specified in the opening tag
Attribute name = “attribute value”
Example
<input type=“text” id=“firstname” name=“firstname”>
type: specifies the type of <input> element to display
id: specifies a unique id for an HTML element can be used by CSS or JavaScript
name: specifies the name of an <input> element used to reference from data after a form is submitted

28. PHP Overview Name comes from Hypertext Preprocessor
Originally Personal Home Page Tools (PHP Tools)
Open source, server-side, HTML embedded scripting language used to create dynamic Web pages
PHP runs on different platforms
PHP is compatible with almost all servers used today, such as Apache, IIS
PHP files have a file extension of ".php", ".php3", or ".phtml"

29. PHP Syntax PHP scripting block <?php Script Here ?>
Can be place anywhere in the HTML code
Can contain HTML tags
Script consists of statements and variables
Script code should end with semicolon (;)
// for single line comment, /* comment */ for multiline comment

30. PHP Variables
Variables are used for storing values, like text strings, numbers or arrays
All variables in PHP start with a $ symbol
In PHP, a variable does not need to be declared before adding a value to it
Variable type is not necessary to be declared
$x=16; $txt="Hello World!";
A variable name should not contain spaces. If a variable name is more than one word, it can be separated with an underscore ($my_string)

31. PHP Variables String concatenation: $a . $b
Single quote and double quote are different
Variable in double quote is replaced by its value
Variable in single quote is shown as it is
Example:
$ _address =
<?php echo “My $ _address”; ?>: displays My
<?php echo ‘My $ _address’; ?>: displays My $ _address

32. $_GET Vs. $_POST
$_GET variable is used to collect values in a form with method="get"
Information sent from a form with the GET method is visible to everyone and has limits on the amount of information to send
$_POST variable is used to collect values from a form sent with method="post"
Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send

33. $_POST Usage <form action="welcome.php" method="post">
Name: <input type="text" name="fname" />
Age: <input type="text" name="age" />
<input type="submit" />
</form>
How we use it in PHP:
Welcome <?php echo $_POST["fname"]; ?>!<br />
You are <?php echo $_POST["age"]; ?> years old

34. Take-home Message Web-based DB Programming is not hard
but it takes time to learn basics and fix bugs
Choose your preferred tools early, and start to get familiar with them
Many tutorials (with examples) available on the web
W3Schools is a great place to start:

35. References Getting starting with CGI Programming in C
PHP related examples, including PHP + MySQL
W3Schools tutorials are generally very helpful, on almost all the tools we covered
Installing, configuring, and developing with XAMPP
Also for using PHP with MySQL
Hugh Williams and David Lane, ``Web Database Applications with PHP and MySQL'' 2nd edition