PHP and MySQL

PHP
• Creates DYNAMIC web pages
– HTML traditionally static
– Contents regenerated every time visit or reload site
• (e.g. can include current time)
• PHP is a scripting language
– Interpreted, not converted to binary executable files
– (Dialogue for play interpreted by actors)
– Strong at communicating with program components written in
other languages
• E.g. can embed PHP statements within HTML

PHP
• Written as a set of CGI binaries in C in 1994 by
R. Lerdorf
– Created to display resume and collect data about
page traffic, e.g. dynamic web pages
– Personal Home Page tools publicly released 1995
– In 1998 became PHP: Hypertext Preprocessor
• PHP parser with web server and web browser,
model similar to MS ASP.NET, Sun JavaServer
Pages

PHP
• Used mainly in server-side scripting
– Can be used from command line interface
– Standalone graphical applications
• Takes input from a file or stream containing text and PHP
instructions
• Outputs stream of data for display
• PHP 4 – parser compiles input to produce bytecode – Zend engine
(better performance than interpreted PHP 3)
• PHP 5 – robust support for OO programming, better support for
MySQL, support for SQLite, performance enhancements

PHP - specifics
• Delimiters: <?php ?> or just <? ?>
• PHP parses code within delimiters
• Code outside delimiter sent to output, not parsed
• Block comments /* */
• Inline comments // #

PHP vs. C++
• Similarities:
– Compiled Language
– Syntax nearly the same (For/While/If)
– Requires semicolons after each statement ;
– Assignment is right to left ($num = 56;)
– Object-Oriented (Class support, inheritance, virtuals,
polymorphism)
– Functions!
– Types are nearly the same (booleans, integers,
strings, etc.)

PHP Versus C++
• Differences:
– Variables begin with $ sign ($name = “John Doe”;)
– No explicit declaration of variable types
– Introduction of “lazy” functions (foreach, explode,
mail)
– No Function Overloading
– “Hidden” functions-within-a-function
– Compiled/interpreted during every page load
– Documented!
– Echo for output

PHP Versus C++
• Web Specific:
– Cookies and “Sessions”
– Dynamic HTML based on user-defined logic
– Interact and process a form’s action
– Process URL Parameters
– Easy Database Integration
– Cross-Site-Scripting (XSS) security hacks -
taken care of by PHP 5
• Allows code injection by web users into web pages
viewed by other users (e.g. phishing attacks)

Introducing/Review HTML
• Hyper Text Markup Language:
– Paired by angled brackets like XML (Ex. <font> </font>)
– Can use a “WYSIWYG” (what you see is what you get) program such as
FrontPage or Dreamweaver for development
– Dynamic web languages such as PHP simply produces HTML

MySQL
• MySQL queries same as SQL in Oracle
• Except it’s freeware!
• Has many of the same capabilities as
traditional DBMSs
– Multi-user, triggers, cursors, etc.
– Doesn’t get performance advantages

MySQL commands
mysql> CREATE TABLE table_name …
INSERT Into table_name …
mysql> LOAD DATA LOCAL INFILE “file_name” INTO
TABLE table_name;
mysql> file_name (containing a query)
mysql> SELECT … FROM … WHERE …
mysql> UPDATE …
mysql> DELETE …

MySQL commands
mysql> SHOW databases;
mysql> USE db_name;
mysql> SHOW tables;
mysql> DESCRIBE table_name;
mysql> create table …
mysql> insert into table values (…
mysql> select * from table_name;

Some php mysql functions
• Mysql_connect (“localhost”, “login”, “password”)
• Mysql_select_db (‘db_name’, $link_id)
• mysql_query (string [, resource $link_id])
– Executes a query, place result in variable, like a cursor
• mysql_error ( )
– Returns error message from previous sql operation
• mysql_fetch_array ($result, how)
– Traverses through cursor of query result
– How is either mysql_assoc (use col. names)
– Or mysql_num (use index number) or mysql_both
• Mysql_num_fields

PHP In Action
<?
echo "Welcome to Vrbsky's DB";
// Connect to MySQL
$link = mysql_connect("localhost", "svrbsky", “password");
if (!$link) {die('Not connected: '. mysql_error()); } // see if connected
// Select DB will use
$dbselected = mysql_select_db('cs457db', $link); // you may not have to do this
mysql_select_db('cs457db') or die ('Could not select database'); // see if worked
// Now the query
$query = "Select * from testit"; // testit has 2 columns, id and age
$result = mysql_query($query, $link);
if (!$result) {die( 'Error in SQL: ' . mysql_error());}
// process results using cursor
while ($row = mysql_fetch_array($result))
{
echo "<hr>"; //horizontal line
echo "id: ". $row["id"] . "<br />";
echo "age: " . $row["age"] . "<br />";
}
mysql_free_result ($result);
mysql_close($link); // disconnecting from MySQL
?>

PHP and MySQL
<?php
$link=mysql_connect (“localhost”, “login”, “password”)
mysql_select_db(‘db') or die('Cannot select database');
$query = 'CREATE TABLE contact( '.
'cid INT NOT NULL AUTO_INCREMENT, '.
'cname VARCHAR(20) NOT NULL, '.
'cemail VARCHAR(50) NOT NULL, '.
'csubject VARCHAR(30) NOT NULL, '.
mysql_query($query, $link) or die (‘Cannot create table’);
mysql_close($link);
?>

Access result row using col. name
<?php
$link=mysql_connect (“localhost”, “login”, “password”)
mysql_select_db(‘db') or die('Cannot select database'); $query =
"SELECT ssn, lname FROM employee";
$result = mysql_query($query, $link);
while($row = mysql_fetch_array($result, MYSQL_ASSOC))
{
echo “SSN :{$row[‘ssn']} <br>" .
“Last : {$row[‘lname']} <br> <br>";
}
// Alterntiavely can use index
// while($row = mysql_fetch_array($result, MYSQL_NUM))
// {
// echo “SSN :{$row[0]} <br>" .
// “Last : {$row[1]} <br><br>";
// }
mysql_close($link);
?>

Forms and input
• Can use HTML to create forms
• Users can input values to use as host
variables in calls to mysql

Our setup
• A machine for us to use PHP and MySQL
• ip address of machine is: 130.160.47.111
• This is a linux machine
– Emacs, vi (I haven’t used this since the ’80s)
• You need to use SSH Secure Shell to Quick
Connect to this machine
• username is 1st
name initial followed by last
name
• E-mail me requesting your password

Our setup
• In order to use your account you must do:
mkdir public_html
chmod 755 public_html/
cd public_html
• Use vi (or whatever) to create new PHP
and HTML files in this directory

Our setup
• Create/save a .php file using an editor
• Sample program:
<? php
Echo “Hello World”
?>
• To run it, from IE, type in ip
address/~yourlogin/filename

MySQL
• To start up MySQL type in:
mysql –u your_login –D your_login –p
It will then prompt you for your password
• You automatically have a db created with
the same name as your login, that is the
–D parameter above

Example html and php
<html>
<head>
</head>
<center>
<!-- The following line results in php code executed after input values in form ->
<form method="post" action="example3.php">
<table>
<tr><td align="left">Dnames</td>
<td><input type="text" name="dname"></td>
</tr>
<tr><td align="left">Lname</td>
<td><input type="text" name="lname" size="15"></td>
</tr>
<tr><colspan="2">
<p align="center">
<input type="submit" value="Enter record">
</td>
</tr>
</table>
</form>
</center>
</html>

Html code
• The previous code uses a form to ask for
input values to a table
• It will execute a php file after input values
in form
• Can use those values in php file, must use
$_POST[‘var_name’]

PHP code
• PHP code places values input from from
into local variables
• Connects to database
• Inserts values into tables
• Prints out values

PHP and MySQL
<?
// This is example3.php used in previous .htm code
$link = mysql_connect("localhost", "svrbsky", “password");
if (!$link) {die('Not connected: '. mysql_error()); }
mysql_select_db(‘svrbsky') or die ('Could not select database');
$dname= $_POST['dname'];
$lname = $_POST['lname'];
$query = "insert into testit2 values ('$dname', '$lname')";
$result = mysql_query($query);
if (!$result) {die('SQL error: ' . mysql_error());}
mysql_close($link);
print "<html><body><center>";
print "<p>You have just entered this record<p>";
print "Dname: $dname<br>";
print "Lname: $lname";
print "</body></html>";
?>

• Won’t this be fun for an assignment?
• Lots of great links on the web to get into
• How to determine what is error?

PHP and MySQL

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