Lecture8

PHP
IT1 Course Slide
Instructor:
Majid Taghiloo

١

Server-Side Dynamic Web Programming
• CGI is one of the most common approaches to server-side programming
Universal support: (almost) Every server supports CGI programming. A great deal of ready-to-use
CGI code. Most APIs (Application Programming Interfaces) also allow CGI p g
( pp g g ) programming.g
Choice of languages: CGI is extremely general, so that programs may be written in nearly any
language. Perl is by far the most popular, with the result that many people think that CGI means
Perl. But C, C++, Ruby, and Python are also used for CGI programming.
Drawbacks: A separate process is run every time the script is requested. A distinction is made
between HTML pages and code.
• Other server-side alternatives try to avoid the drawbacks
Server-Side Includes (SSI): Code is embedded in HTML pages, and evaluated on the server while
the pages are being served. Add dynamically generated content to an existing HTML page, without
having to serve the entire page via a CGI program
program.
Active Server Pages (ASP, Microsoft) : The ASP engine is integrated into the web server so it does
not require an additional process. It allows programmers to mix code within HTML pages instead of
writing separate programs. (Drawback(?) Must be run on a server using Microsoft server software.)
programs software )
Java Servlets (Sun): As CGI scripts, they are code that creates documents. These must be
compiled as classes which are dynamically loaded by the web server when they are run.
Java Server Pages (
g (JSP): Like ASP, another technology that allows developers to embed Java in
) , gy p
web pages.
٢

PHP
• developed in 1995 by Rasmus Lerdorf (member of the Apache Group)
originally designed as a tool for tracking visitors at Lerdorf's Web site
within 2 years, widely used in co ju c o with the Apache se e
yea s, de y conjunction e pac e server
developed into full-featured, scripting language for server-side programming
free, open-source
server plug-ins exist for various servers
plug ins
now fully integrated to work with mySQL databases

• PHP is similar to JavaScript, only it’s a server-side l
i i il t J S i t l it’ id language
PHP code is embedded in HTML using tags
when a page request arrives, the server recognizes PHP content via the file extension (.php
or .phtml)
the server executes the PHP code, substitutes output into the HTML page
the resulting page is then downloaded to the client
user never sees the PHP code, only the output in the page

• The acronym PHP means (in a slightly recursive definition)
PHP: Hypertext Preprocessor
٣

What do You Need?
• Our server supports PHP
O PHP
– You don't need to do anything special! *
– You don't need to compile anything or install any extra tools!
– Create some .php f l in your web d
h files b directory ‐ and the server will parse them f
d h ll h for
you.
* Slightly different rules apply when dealing with an SQL database (as will be explained when we get to that point).

• Most servers support PHP
– Download PHP for free here: http://www.php.net/downloads.php
– Download MySQL for free here: http://www mysql com/downloads/index html
http://www.mysql.com/downloads/index.html
– Download Apache for free here: http://httpd.apache.org/download.cgi

(Note: All of this is already present on the CS servers, so you need not do any
installation yourself to utilize PHP on our machines.)

۴

Help with PHP
Loads of information, including help on individual PHP
functions may be found at
http://uk.php.net/
h // k h /

۵

Basic PHP syntax
A PHP scripting block always starts with <?php and ends with ?> A PHP scripting block
?>.
can be placed (almost) anywhere in an HTML document.
<html>
<!‐‐ hello.php COMP519 ‐‐> print and echo
i t h
<head><title>Hello World</title></head>
<body> for output
<p>This is going to be ignored by the PHP interpreter.</p>

<?php echo ‘<p>While this is going to be parsed.</p>‘; ?> a semicolon (;) at the
<p>This will also be ignored by PHP.</p> end of each statement
<?php i t(‘< >H ll
<? h print(‘<p>Hello and welcome t <i> </i> page!</p>');
d l to <i>my</i> !</ >')
?>

<?php

//This is a comment
// for a single-line comment
single line
/* /* and */ for a large
This is
a comment
comment block.
block
*/
?>

</body>
</html>

۶
The server executes the print and echo statements, substitutes output.

Scalars
All variables in PHP start with a $ sign symbol. A variable's type is determined by the
$ g y yp y
context in which that variable is used (i.e. there is no strong‐typing in PHP).
<html><head></head>
<!‐‐ scalars.php
<! scalars php COMP519 ‐‐> >
<body> <p>
<?php
$foo = true; if ($foo) echo "It is TRUE! <br /> n";
$txt='1234'; echo "$txt <br /> n";
Four scalar types:
$a = 1234; echo "$a <br /> n"; boolean
b l
$a = ‐123;
echo "$a <br /> n"; true or false
$a = 1.234;
echo "$a <br /> n";
$a br / n ;
integer,
$a = 1.2e3; float,
echo "$a <br /> n";
$a = 7E‐10; floating point numbers
echo "$a <br /> n";
echo 'Arnold once said: "I'll be back , "<br /> n";
Arnold I ll back"' <br n ;
stringg
$beer = 'Heineken'; single quoted
echo "$beer's taste is great <br /> n";
$str = <<<EOD double quoted
Example of string
spanning multiple lines
using “heredoc” syntax.
EOD;
echo $str;
?>
</p>
</body>
</html>
٧

Arrays
y
An array in PHP is actually an ordered map. A map is a type that maps values to keys.
array() = creates arrays
<?php
$arr = array("foo" => "bar", 12 => true); key = either an integer or a string.
echo $arr["foo"]; // bar
echo $arr[12]; // 1 value = any PHP type.
?>

if no key given (as in example), the PHP
<?php
array(5 => 43, 32, 56, "b" => 12);
interpreter uses (maximum of the integer indices +
array(5 => 43, 6 => 32, 7 => 56, "b" => 12);
y( ) 1).
?>
if an existing key, its value will be overwritten.

<?php
p p
$arr = array(5 => 1, 12 => 2);
can set values in an array
foreach ($arr as $key => $value) { echo $key, ‘=>’,
$value); }
$arr[] = 56; // the same as $arr[13] = 56; unset() removes a key/value pair
$arr[ x ]
$arr["x"] = 42; // adds a new element
unset($arr[5]); // removes the element
unset($arr); // deletes the whole array
$a = array(1 => 'one', 2 => 'two', 3 => 'three');
array_values() makes reindexing effect
unset($a[2]); (indexing numerically)
$b = array_values($a);
l ($ )
?>

٨ *Find more on arrays

Constants
A constant is an identifier (name) for a simple value. A constant is case‐sensitive by
A constant is an identifier (name) for a simple value A constant is case sensitive by
default. By convention, constant identifiers are always uppercase.

<?php

// Valid constant names
define("FOO", "something");
define("FOO2", "something else");
define("FOO_BAR", "something more");

// Invalid constant names (they shouldn’t start
shouldn t You can access constants
// with a number!)
anywhere in your script
define("2FOO", "something"); without regard to scope.
// This is valid, b t should b avoided:
Thi i lid but h ld be id d
// PHP may one day provide a “magical” constant
// that will break your script

define("__FOO__", "something");

?>

٩

Operators Example Is the same as
• Arithmetic Operators: +, ‐, *,/ , %, ++, ‐‐ x+=y x=x+y
x‐=y x=x‐y
• Assignment Operators: =, +=, = =, /=,
Assignment Operators: = += ‐=, *= /= %= x*=y
* x=x*y
*
x/=y x=x/y
x%=y x=x%y

• Comparison Operators: ==, !=, >, <, >=, <=
• Logical Operators: &&, ||, !
• String Operators: . and .= (for string concatenation)

$a = "Hello ";
$b = $a . "World!"; // now $b contains "Hello World!"

$a = "Hello ";
$a .= "World!";

١٠

Conditionals: if else
Can execute a set of code depending on a condition

<html><head></head> if (condition)
( )
<!‐‐ if‐cond.php COMP519 ‐‐>
<body> code to be executed if condition
is true;
<?php
$d=date("D");
$d d (" ") else
echo $d, “<br/>”; code to be executed if condition
if ($d=="Fri")
echo "Have a nice weekend! <br/>";
is false;
else
l
echo "Have a nice day! <br/>";

$x=10;
date() is a built-in PHP function
if ($x==10)
($ 10) that can be called with many
{ different parameters to return the
echo "Hello<br />";
echo "Good morning<br />"; date (and/or local time) in
} various f
i formats
t
?>
In this case we get a three letter
</body>
/b d
</html>
string for the day of the week.
١١

Conditionals: switch
Can select one of many sets of lines to execute

<html><head></head>
<body>
<!–‐ switch‐cond.php COMP519 ‐‐> switch (expression)
<?php
$x = rand(1,5); // random integer
{
echo “x = $ <br/><br/>”;
$x / / case label1:
switch ($x) code to be executed if expression =
{
case 1:
label1;
echo "Number 1"; ; break;
break; case label2:
case 2:
echo "Number 2";
code to be executed if expression =
break; label2;
case 3: break;
echo "Number 3";
break;
default:
default: code to be executed
echo "No number between 1 and 3"; if expression is different
break;
b k
}
from both label1 and label2;
?> break;
}
</body>
</html>

١٢

Looping: while and do‐while
Can loop depending on a condition
Can loop depending on a condition

<html><head></head> <html><head></head>
<body>
y <body>
y

<?php <?php
$i=1; $i=0;
while($i <= 5) do
{ {
echo "The number is $i <br />"; $i++;
$i++; echo "The number is $i <br />";
} }
?> while($i <= 10);
?>
</body>
</html> </body>
</html>

loops through a block of code if and as long as, a specified
if, as
condition is true loops through a block of code once, and then repeats the
loop as long as a special condition is true (so will always
execute at least once)

١٣

Looping: for and foreach
p g
Can loop depending on a "counter"

<?php <?php
for ($i=1; $i<=5; $i++) $a_array = array(1, 2, 3, 4);
{ foreach ($a_array as $value)
echo "Hello World!<br />"; {
} $value = $value * 2;
?> echo “$value <br/> n”;
}
?>

loops through a block of code a specified number
of times <?php
$a_array=array( a b c );
$a array=array("a","b","c");
foreach ($a_array as $key => $value)
{
echo $key." = ".$value."n";
}
?>

loops through a block of code for each element in an
p g
array

١۴

User Defined Functions
Can define a function using syntax such as the following:

<?php
function foo($arg 1, $arg 2, /* ..., */ $arg n)
($ g_ , $ g_ , / , / $ g_ ) Can also define conditional functions, functions
functions
{
echo "Example function.n";
within functions, and recursive functions.
return $retval;
}
?>

Can return a value of any type

<?php <?php
function square($num) function small_numbers()
{ {
return $num * $num; return array (0, 1, 2);
} }
echo square(4); list ($zero, $one, $two) = small_numbers();
?> echo $zero, $one, $two;
?>

<?php
function takes_array($input)
{
echo "$input[0] + $input[1] = ", $input[0]+$input[1];
$input[0]
}
takes_array(array(1,2));
?> ١۵

Variable Scope
The scope of a variable is the context within which it is defined.

<?php
? h
$a = 1; /* limited variable scope */
function Test()
{
The scope is local within functions,
echo $
h $a; and hence the value of $a is
/* reference to local scope variable */ undefined in the “echo” statement.
}
Test();
?>
?

<?php
<?php
p p function Test()
$a = 1; {
$b = 2; global static $a = 0; static
function Sum() echo $a;
{ refers to its global $a++; does not lose its value.
global $a $b;
$a, version.
version }
$b = $a + $b; Test1();
} Test1();
Sum(); Test1();
echo $b; ?>
?>

١۶

Including Files
The include() statement includes and evaluates the specified file.

<?php
vars.php
function foo()
<?php
{
global $color;
$color = 'green';
$fruit = 'apple';
include ('vars.php‘);
?>
echo "A $color $fruit";
}
test.php
<?php
/
/* vars.php is in the scope of foo() so *
p p p ()
* $fruit is NOT available outside of this *
echo "A $color $fruit"; // A
* scope. $color is because we declared it *
* as global. */
include 'vars.php';
foo(); // A green apple
echo "A $color $fruit"; // A green apple
echo "A $color $fruit"; // A green
?>
?>

*The scope of variables in “included” files depends on where the “include” file is added!
١٧
You can use the include_once, require, and require_once statements in similar ways.

PHP Information
The phpinfo() function is used to output PHP information about the version installed on the
server, parameters selected when installed, etc.
, parameters selected when installed, etc.

<html><head></head>
INFO_GENERAL The configuration line,
<!– info.php COMP519
php.ini location,
<body>
build date,
<?php
Web Server,
// Show all PHP information
System and more
phpinfo();
?>
INFO_CREDITS PHP 4 credits
<?php
INFO_CONFIGURATION Local and master values
// Show only the general information
for php directives
phpinfo(INFO_GENERAL);
phpinfo(INFO GENERAL);
?>
INFO_MODULES Loaded modules
</body>
</html>
INFO_ENVIRONMENT Environment variable
information
INFO_VARIABLES All predefined variables
from EGPCS

INFO_LICENSEPHP license information
INFO_ALL
INFO ALL Shows all of the above (default)

١٨

Server Variables
The $_SERVER array variable is a reserved variable that contains all server information.

<html><head></head>
h l h d /h d
<body>

<?php
echo "Referer: " . $_SERVER["HTTP_REFERER"] . "<br />";
_ [ _ ]
echo "Browser: " . $_SERVER["HTTP_USER_AGENT"] . "<br />";
echo "User's IP address: " . $_SERVER["REMOTE_ADDR"];
?>

</body>
</html>

The $_SERVER is a super global variable, i.e. it's available in all scopes of a PHP script.

١٩

File Open

The fopen("file_name","mode") function is used to open files in PHP.

r Read only. r+ Read/Write.
w Write only. w+ Read/Write.
a Append.
Append a+ Read/Append.
Read/Append
x Create and open for write only. x+ Create and open for read/write.

<?php For w, and a, if no file exists, it tries to create it (use with caution, i.e.
$fh=fopen("welcome.txt","r"); check that this is the case, otherwise you’ll overwrite an existing file).
?>

For x if a file exists, it returns an error.
<?php
if If th f
the fopen() f ti iis unable to open the specified file, it
() function bl t th ifi d fil
( !($fh=fopen("welcome.txt","r")) ) returns 0 (false).
exit("Unable to open file!");
?>

٢٠

File Workings
fclose() closes a file.
feof() determines if the end is true
true.

fgetc() reads a single character fgets() reads a line of data

fwrite(), fputs () writes a string with and without n
(), p g
file() reads entire f into an array
file

<?php <?php
$myFile = "welcome.txt";
welcome.txt ; $myFile = "welcome.txt";
welcome.txt ;
if (!($fh=fopen($myFile,'r'))) $fh = fopen($myFile, 'r');
exit("Unable to open file."); $theData = fgets($fh);
while (!feof($fh)) fclose($fh);
{ echo $theData;
$x=fgetc($fh); ?>
echo $x;
}
fclose($fh);
?> <?php
p p
$myFile = "testFile.txt";
$fh = fopen($myFile, 'a') or die("can't open file");
$stringData = "New Stuff 1n";
<?php fwrite($fh, $stringData);
$lines = fil (' l
$li file('welcome.txt');
') $stringData = "New Stuff 2n";
New 2n ;
foreach ($lines as $l_num => $line) fwrite($fh, $stringData);
{ fclose($fh);
echo "Line #{$l_num}:“ .$line.”<br/>”; ?>
}
?>

٢١

Form Handling
Any form element is automatically available via one of the built‐in PHP variables (provided the element has a “name” defined with
y o e e e t s auto at ca y a a ab e a o e o t e bu t a ab es (p o ded t e e e e t as a a e de ed t
it).

<html>
<‐‐ form.html COMP519 ‐‐>
<body>
<form action="welcome.php" method="POST">
Enter your name: <input type="text" name="name" /> <br/>
Enter your age: <input type="text" name="age" / <br/>
" " " " /> b /
<input type="submit" /> <input type="reset" />
</form>
</body>
</html>

<html> $_POST
_
<!–‐ welcome.php COMP 519 ‐‐>
! l h
contains all POST data.
<body>
$_GET
Welcome <?php echo $_POST["name"].”.”; ?><br />
contains all GET data.
You are <?php echo $_POST["age"]; ?> years old!

</body>
</html>

٢٢

Cookie Workings
setcookie(name,value,expire,path,domain) creates cookies.
ki ( l i h d i ) ki

<?php
setcookie("uname", $_POST["name"], time()+36000);
?>
<html>
<body> NOTE:
<p> setcookie() must appear
Dear <?php echo $_POST["name"] ?>, a cookie was set on this
BEFORE <html> (or any output)
page! The cookie will be active when the client has sent the
cookie back to the server. as it’s part of the header
</p> information sent with the page.
</body>
</html>

<html>
<body> $_COOKIE
<?php contains all COOKIE data.
if ( isset($_COOKIE["uname"]) )
echo "Welcome " . $_COOKIE["uname"] . "!<br />";
else isset()
echo "You are not logged in!<br />"; finds out if a cookie is set
?>
</body>
</html>
/
use the cookie name as a variable

٢٣

Getting Time and Date
date() and time () formats a time or a date
formats a time or a date.

<?php
//Prints something like Monday
like:
echo date("l");
date() returns a string formatted according to
//Like: Monday 15th of January 2003 05:51:38 AM
the specified format.
echo date("l jS of F Y h:i:s A");

//Like: Monday the 15th
echo date("l the jS");
?>

<?php
p p
$nextWeek = time() + (7 * 24 * 60 * 60);
// 7 days; 24 hours; 60 mins; 60secs time() returns current Unix
echo 'Now: '. date('Y‐m‐d') ."n"; timestamp
echo 'Next Week: '. date('Y‐m‐d', $nextWeek) ."n";
?>

*Here is more on date/time formats: http://uk.php.net/manual/en/function.date.php

٢۴

Required Fields in User‐Entered Data
A multipurpose script which asks users for some basic contact information and then checks to
l h h k f b f d h h k
see that the required fields have been entered.

<html>
<!‐‐ form_checker.php COMP519 ‐‐>
<head>
<title>PHP Form example</title>
</head>
<body>
<?php
/*declare some functions*/

Print Function
P i t F ti
function print_form($f_name, $l_name, $email, $os)
{
?>

<form action="form_checker.php" method=“POST">
First Name: <input type="text" name="f_name" value="<?php echo $f_name?>“ /> <br/>
Last Name <b>*</b>:<input t
L tN <b>*</b> <i t type="text" name="l_name" value="<?php echo $l
"t t" "l " l "<? h h $l_name?>“ /> <b />
?>“ <br/>
Email Address <b>*</b>:<input type="text" name="email" value="<?php echo $email?>“ /> <br/>
Operating System: <input type="text" name="os" value="<?php echo $os?>“ /> <br/><br/>
<input type="submit" name="submit" value="Submit“ /> <input type=“reset“ />
</form>

<?php
} //** end of “print_from” function
٢۵

Check and Confirm Functions
function check_form($f_name, $l_name, $email, $os)
{
if (!$l_name||!$email){
echo "<h3>You are missing some required fields!</h3>";
print_form($f_name, $l_name, $email, $os);
}
else{
confirm_form($f_name, $l_name, $email,
confirm form($f name $l name $email $os);
}
} //** end of “check_form” function

function confirm_form($f_name, $l_name, $email, $os)
{
?>

<h2>Thanks! Below is the information you have sent to us.</h2>
<h3>Contact Info</h3>

<?php
echo "N
h "Name: $f$f_name $l
$l_name <br/>";
b/ "
echo "Email: $email <br/>";
echo "OS: $os";
} //** end of “confirm_form” function

٢۶

Main Program
/*Main Program*/

if (!$_POST["submit"])
{
?>

<h3>Please enter your information</h3>
<p>Fields with a "<b>*</b>" are required.</p>

<?php
print_form("","","","");
}
else{
check_form($_POST["f_name"],$_POST["l_name"],$_POST["email"],$_POST["os"]);
}
?>

</body>
</html>

٢٧

Introduction to SQL
SQL is an ANSI (American National Standards Institute) standard computer language
for accessing and manipulating databases.
• SQL stands for Structured Query Language
• using SQL can you can
– access a database
– execute queries, and retrieve data
– insert, delete and update records
• SQL works with database programs like MS Access, DB2, Informix, MS SQL Server, Oracle, Sybase, mySQL, etc.

Unfortunately, there are many different versions. But, they must support the same major keywords in a similar manner such as
SELECT, UPDATE, DELETE, INSERT, WHERE, etc.

Most of the SQL database programs also have their own proprietary extensions!

٢٨

SQL Database Tables
A database most often contains one or more tables. Each table is identified by a
name (e.g. "Customers" or "Orders"). Tables contain records (rows) with data.

For example, a table called "Persons":

LastName
L tN FirstName
Fi tN Address
Add City
Cit
Hansen Ola Timoteivn 10 Sandnes
Svendson Tove Borgvn 23 Sandnes
Pettersen Kari Storgt 20 Stavanger

The table above contains three records (one for each person) and four columns (LastName,
FirstName, Address, and City).

SQL Queries
With SQL, you can query a database and have a result set returned.

A query like thi
lik this:

SELECT LastName FROM Persons;

gives a result set like this:

LastName
Hansen
a se
Svendson
Pettersen
The mySQL database system requires a semicolon at the end of
the SQL statement!

SQL Data Languages
The query and update commands together form the Data Manipulation Language
(DML) part of SQL:
• SELECT - extracts data from a database table
• UPDATE - updates data in a database table
• DELETE - deletes data from a database table
• INSERT INTO - inserts new data into a database table

The Data Definition Language (DDL) part of SQL permits database tables to be created
or deleted:
• CREATE TABLE - creates a new database table
• ALTER TABLE - alters (changes) a database table
• DROP TABLE - deletes a database table
• CREATE INDEX - creates an index (search key)
• DROP INDEX - deletes an index

*Here we will use some of them in mySQL
٣١

Logging into mySQL Server
You
Y can l i
log into our mySQL server f
SQL from Li
Linux b typing i the prompt
by i in h

bash‐2.05b$ mysql ‐h mysql martin –u martin

Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 209201 to server version: 5.0.22

Type 'help;' or 'h' for help. Type 'c' to clear the buffer.

mysql>

From here you can create modify and drop tables, and modify the data in your tables
create, modify, tables tables.
But first, you must specify which database on the server you want to use (you have only
one, however).

mysql> use martin;

Database changed
٣٢

Technical note
• Y probably d ’t need t worry about thi b t th
You b bl don’t d to b t this, but thought I would
ht ld
mention it here…

Most books and on‐line tutorials assume the database server is
running on the same machine as everything else, and that the user
is "root".
root
Neither of these are true here. Wherever you see "localhost",
replace it by "mysql" Wherever you see "root", replace it with your
username.

(Ignore this if you don’t understand it for now, or are not consulting
other references.)

٣٣

Creating a Table
You
Y can create a table you might use f the upcoming project. For example,
bl i h for h i j l

mysql> CREATE TABLE students(
Hit Enter after each line (if you
‐> num INT NOT NULL AUTO_INCREMENT,
want). MySQL doesn’t try to
‐> f_name VARCHAR(48), interpret the command itself until
‐> l_name VARCHAR(48), it sees a semicolon (;)
‐> student_id INT, (The “->” characters you see are
‐> email VARCHAR(48), not typed by you.)
‐> PRIMARY KEY(num));

Query OK, 0 rows affected (0.02 sec)

*If the server gives you a big ERROR, just try again from the top!

٣۴

Inserting Data
Using INSERT INTO you can insert a new row into your table. For example,
table example

mysql> INSERT INTO students
‐> VALUES(NULL,’Russell’,’Martin’,396640,‘martin@csc.liv.ac.uk');

Query OK, 1 row affected (0.00 sec)

Using SELECT FROM you select some data from a table.
g y

mysql> SELECT * FROM students;

+‐‐‐‐‐+‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
| num | f_name | l name | student id | email
f name l_name student_id |
+‐‐‐‐‐+‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
| 1 | Russell | Martin | 396640 | martin@csc.liv.ac.uk |
+‐‐‐‐‐+‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐‐‐+‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐+
1 row in set (0.00 sec)

٣۶

Getting Data Out of the Table
• The SELECT command is the main way of getting data out of a table or set of
table,
tables.
SELECT * FROM students;
Here the asterisk means to select (i.e. return the information in) all columns.

You can specify one or more columns of data that you want, such as
SELECT f name,l name FROM students;
f_name,l_name
+---------+--------+
| f_name | l_name |
+---------+--------+
| Russell | Martin |
| James | Bond |
+---------+--------+

٣٨

The Final Table (cont.)
. . .
. . .
mysql> INSERT INTO students VALUES(NULL,‘Hugh,‘Milner',75849789,‘hugh@poughkeepsie.ny‘,
CURRENT_DATE, 2);

Note: CURRENT_DATE is a built-in SQL command which (as expected)
gives the current (local) date.

+-----+---------+----------+------------+----------------------------+------------+------+
| num | f_name | l_name | student_id | email | date | gr
g |
+-----+---------+----------+------------+----------------------------+------------+------+
| 1 | Russell | Martin | 396310 | martin@csc.liv.ac.uk | 2007-11-15 | 3 |
| 5 | Kate | Ash | 124309 | kate@ozymandius.co.uk | 2007-11-16 | 3 |
| 3 | James | Bond | 7 | bond@csc.liv.ac.uk | 2007-11-15 | 1|
| 4 | Bob | Jones | 12190 | bob@nowhere.com | 2007-11-16 | 3 |
| 6 | Pete | Lofton | 76 | lofton@iwannabesedated.com | 2007-11-17 | 2 |
| 7 | Polly | Crackers | 1717 | crackers@polly.org | 2007-11-17 | 1|
| 8 | Hugh | Milner | 75849789 | hugh@poughkeepsie.ny | 2007-11-17 | 2 |
+-----+---------+----------+------------+----------------------------+------------+------+
mysql> exit
۴۴
Bye

Other SQL Commands
• SHOW tables; gives a list of tables that have been defined in the database
• ALTER TABLE students DROP email; would drop the “email” column from all
records
• DROP TABLE students; deletes the entire “students” table, and its definition (use
students (use
the DROP command with extreme care!!)
• DELETE FROM students; removes all rows from the “students” table (so once
again, use the DELETE command with great caution), the table definition remains
to be used again
• A more useful command is something like
DELETE FROM students WHERE (num > 5) AND (num <= 10);
which selectively deletes students based on their “num” values (for example)
num example).

• HELP; gives the SQL help
• HELP DROP; gives help on the DROP command, etc.

۴۵

Backing up/restoring a mySQL
database
• You can back up an entire database with a command such as
mysqldump –h mysql –u martin martin > backup.sql

(Run from the Unix command line )line.)
• This gives a script containing SQL commands to reconstruct the
table structure (of all tables) and all of the data in the table(s).
( ) ()
• To restore the database (from scratch) you can use this type of
Unix command:
mysql –h mysql –u martin martin < backup sql
h u backup.sql
(Use with caution, as this can overwrite your database.)
• Other commands are possible to backup/restore only certain
tables or items in tables etc if that is what you desire For
tables, etc. desire.
example
mysqldump –h mysql –u martin martin books clients> backup.sql

stores information about the “books” and “clients” tables in the
books clients
“martin” database.
۴۶

Putting Content into Your Database
with PHP
We can simply use PHP functions and mySQL queries together:

• Connect to the database server and login (this is the PHP command to do so)
mysql_connect("host","username","password");
Host: mysql

• Choose the database Database: martin

mysql_select_db("database"); Username: martin
Password: <blank>

• Send SQL queries to the server to add, delete, and modify data
mysql_query("query"); (use the exact same query string as you would
normally use in SQL, without the trailing semi‐colon)

• Close the connection to the database server (to ensure the information is stored properly)
mysql_close();

• Note: For this to work properly on the UoL server, you must access the PHP script through the cgi server
(http://cgi.csc.liv.ac.uk/~martin/getstuff.php for example).
۴٧

Student Database: data_in.php
<html>
<head>
<title>Putting Data in the DB</title>
</head>
<body>
<?php
/*insert students into DB*/
if(isset($_POST["submit"])) {

$db = mysql_connect("mysql”, ”martin");
mysql_select_db("martin");

$date=date("Y-m-d");
$d t d t ("Y d") /* G t th current date in the right SQL f
Get the t d t i th i ht format
t */

$sql="INSERT INTO students VALUES(NULL,'“ . $_POST[“f_name"] . "','“ .
$_POST["l_name"] . "',“ . $_POST["student_id"] . ",'“ . $_POST["email"] .
"','“ . $date . "',“ . $_POST["gr"] . ")"; /* construct the query
*/

mysql_query($sql); /* execute the query */
mysql_close();

echo"<h3>Thank you. The data has been entered.</h3> n";

echo'<p><a href="data_in.php">Back to registration</a></p>‘ . “n”;

echo'<p><a href "data out php">View the student lists</a></p>‘ .”n”;
href="data_out.php">View ”n”;

}
۴٨

Student Database: data_in.php
_ p p
else {
?>
<h3>Enter your items into the database</h3>
<form action="data_in.php" method="POST">
First Name: <input type="text" name=“f_name“ /> <br/>
Last Name: <input type="text" name=“l_name“ /> <br/>
p yp
ID: <input type="text" name=“student_id“ /> <br/>
email: <input type="text" name=“email“ /> <br/>
Group: <select name="gr">
<option value ="1">1</option>
p p
</select><br/><br/>
<input type="submit" name="submit“ /> <input type="reset“ />
p yp p yp
</form>

<?php
}
?>

</body>
</html>

۴٩

Getting Content out of Your Database
with PHP
ith
Similarly,
Similarly we can get some information from a database:

• Connect to the server and login, choose a database
mysql_connect("host","username","password");
l t("h t" " "" d")
mysql_select_db("database");

• S d an SQL query t th server t select d t from th d t b
Send to the to l t data f the database into an array
i t
$result=mysql_query("query");
• Either, look into a row and a fieldname
,
$num=mysql_numrows($result);
$variable=mysql_result($result,$i,"fieldname");
• Or, fetch rows one by one
$row=mysql_fetch_array($result);

• Close the connection to the database server
mysql_close();
۵٠

Student Database: data_out.php
<html>
<head>
<title>Getting Data out of the DB</title>
</head>
<body>
<h1> Student Database </h1>
<p> Order the full list of students by
<a href="data_out.php?order=date">date</a>,
<href="data_out.php?order=student_id">id</a>, or
by <a href="data_out.php?order=l_name">surname</a>.
</p>

<p>
<form action="data_out.php" method="POST">
Or only see the list of students in group
<select name="gr">
</select>
<br/>
<input type="submit" name="submit“ />
</form>
</p>

۵١

Student Database: data_out.php
<?php
p p
/*get students from the DB */
$db = mysql_connect("mysql",“martin");
mysql_select_db(“martin", $db);

switch($_GET["order"]){
case 'date': $sql = "SELECT * FROM students ORDER BY date"; break;
case ‘student_id': $sql = "SELECT * FROM students ORDER BY student_id"; break;
case ‘l_name': $sql = "SELECT * FROM students ORDER BY l_name"; break;

default: $sql = “SELECT * FROM students”; break;
}
if(isset($_POST["submit"])){
$sql = “SELECT * FROM students WHERE gr=“ . $_POST["gr"];
}

$result=mysql_query($sql); /* execute the query */
while($row=mysql_fetch_array($result)){
echo "<h4> Name: “ . $row["l_name"] . ', ‘ . $row["f_name"] . "</h4> n";
echo "<h5> ID: “ . $row[“student_id"] . "<br/> Email: “ . $row["email"] . "<br/> Group: “ . $row["gr"] . "<br/> Posted:
“ . $row["date"] . "</h5> n";
}
mysql_close();
?>
</body>
</html>

۵٢

Can Do Even More with PHP

• Can create tables in PHP
• Can delete
C d l t rows and columns
d l
• Can make updates
• Can make queries to several tables
• Can get connected to several databases

* Find more iinformation on PHP/ SQL
Fi d f ti PHP/mySQL

۵٣

Learning Outcomes

In these last lectures you have learned
What is SQL
How to access mySQL database
How to create a basic mySQL database
How to use some basic queries
How t
H to use PHP and mySQL
d SQL

۵۴

Using several tables

• mySQL (like any other database system that uses SQL) is a relational
database, meaning that it’s designed to work with multiple tables, and it
allows you to make queries that involve several tables
tables.
• Using multiple tables allows us to store lots of information without much
duplication.
duplication
• Allows for easier updating (both insertion and deletion).
• We can also perform different types of queries, combining the
queries
information in different ways depending upon our needs.

۵۵

mysql> describe itemlist;
+-------------+---------+------+-----+---------+----------------+
| Field | T pe
Type | N ll | Ke | Defa lt | E t a
Null Key Default Extra |
+-------------+---------+------+-----+---------+----------------+
| item_id | int(11) | NO | PRI | NULL | auto_increment |
| purchase_id | int(11) | NO | | | |
| book id
book_id | int(11) | NO | | | |
+-------------+---------+------+-----+---------+----------------+

mysql> describe books;
+---------+-------------+------+-----+---------+----------------+
+---------+-------------+------+-----+---------+----------------+
| book id | int(11)
book_id | NO | PRI | NULL | auto_increment |
auto increment
| title | varchar(50) | NO | | | |
| pages | int(11) | YES | | NULL | |
+---------+-------------+------+-----+---------+----------------+
(0 00

mysql>

۵٧

The idea here is that clients can make multiple purchases. Each
purchase will be assigned a unique id, but can consist of multiple
items. Each item is a book, which can be purchased by many
different people
people.

Defining the tables in this fashion allows us to avoid (
g (excessive))
repetition of information, and lets us query the data in different
fashions.

The “id” fields are the keys that we use to tie the various tables together,
namely a customer (or client) with “client id” will make several
client_id
purchases. We can identify their purchases by searching for
matches of the client_id in the purchases table.

Similarly, we can find the actual items that comprise a particular
purchase by searching for the purchase id key in the itemlist table
purchase_id table.
۵٨

mysql> SELECT * FROM purchases;
+-------------+-----------+------------+
| purchase_id | client_id | date |
+-------------+-----------+------------+
| 1 | 1 | 2007-11-09 |
| 2 | 1 | 2007-11-10 |
| 4 | 2 | 2007-11-20 |
| 5 | 4 | 2007-11-20 |
| 6 | 3 | 2007 11 21 |
2007-11-21
| 7 | 5 | 2007-11-25 |
| 8 | 3 | 2007-11-25 |
+-------------+-----------+------------+

mysql> SELECT * FROM itemlist;
+---------+-------------+---------+
| item_id | purchase_id | book_id |
+---------+-------------+---------+
| 1 | 1 | 2 |
| 2 | 1 | 6 |
| 3 | 1 | 3 |
| 4 | 2 | 4 |
| 5 | 2 | 5 |
| 6 | 4 | 5 |
| 7 | 4 | 6 |
| 8 | 5 | 1 |
| 9 | 5 | 3 |
| 10 | 6 | 5 |
| 11 | 7 | 2 |
| 12 | 8 | 3 |
+---------+-------------+---------+

mysql>
۶٠

Advanced Queries
• We can link these tables together by queries of this type:

myql> SELECT * from clients, purchases WHERE clients.client_id=purchases.client_id ORDER BY purchase_id;
+----------+---------+--------+--------------------------+----------------+----------+-------------+-----------+------------+
|client_id | f_name | l_name | address | city | postcode | purchase_id | client_id | date |
-----------+---------+--------+--------------------------+----------------+----------+-------------+-----------+------------+
| 1 | Russell | Martin | Dept of Computer Science | Liverpool | L69 3BX | 1| 1 | 2007-11-09 |
| 1 | Russell | Martin | Dept of Computer Science | Liverpool | L69 3BX | 2| 1 | 2007 11 10 |
2007-11-10
| 2 | Bob | Milnor | 12 Peachtree Ln | Liverpool | L12 3DX | 4| 2 | 2007-11-20 |
| 4 | Larry | Vance | 76 Jarhead Ln | Liverpool | L12 4RT | 5| 4 | 2007-11-20 |
| 3 | Sarah | Ford | 542b Jersey Rd | West Kirby | L43 8JK | 6| 3 | 2007-11-21 |
| 5 | Paul | Abbott | 90 Crabtree Pl | Leamingotn Spa | CV32 7YP | 7| 5 | 2007-11-25 |
| 3 | Sarah | Ford | 542b Jersey Rd | West Kirby | L43 8JK | 8| 3 | 2007-11-25 |
+-----------+---------+--------+--------------------------+----------------+----------+-------------+-----------+------------+
7 rows in set (0 01 sec)
(0.01

mysql>

So you can see that this query gives us all of the purchase orders
that have been placed by the clients (but not the number of items, or the items
۶١
themselves).

• You can see that the “client_id” field is repeated. This is because we selected all columns
(
(using the * option) in both tables, and it appears in each table.
g p ) pp

• To avoid this repeated information, we can make a query like:

mysql> SELECT clients.client_id, f_name, l_name, address, city, postcode, purchases.purchase_id,date from
clients, purchases WHERE clients.client_id=purchases.client_id ORDER BY purchase_id;
+-----------+---------+--------+--------------------------+----------------+----------+-------------+------------+
| client_id | f_name | l_name | address
ce d a e a e add ess | city
c y | postcode | purchase id | date
pos code pu c ase_ d da e |
+-----------+---------+--------+--------------------------+----------------+----------+-------------+------------+
| 1 | Russell | Martin | Dept of Computer Science | Liverpool | L69 3BX | 1 | 2007-11-09 |
| 1 | Russell | Martin | Dept of Computer Science | Liverpool | L69 3BX | 2 | 2007-11-10 |
| 2 | B b | Milnor | 12 P ht Ln
Bob Mil Peachtree L | Liverpooll | L12 3DX
Li | 4 | 2007 11 20 |
2007-11-20
| 4 | Larry | Vance | 76 Jarhead Ln | Liverpool | L12 4RT | 5 | 2007-11-20 |
| 3 | Sarah | Ford | 542b Jersey Rd | West Kirby | L43 8JK | 6 | 2007-11-21 |
g p 7 | 2007-11-25 |
| 3 | Sarah | Ford | 542b Jersey Rd | West Kirby | L43 8JK | 8 | 2007-11-25 |
+-----------+---------+--------+--------------------------+----------------+----------+-------------+------------+

mysql>

The “NATURAL JOIN” option can obtain the same result as above, as they share a single key.
NATURAL JOIN

mysql> SELECT * FROM clients NATURAL JOIN purchases;
۶٢

More Complex Queries
• We can create most any type of query that you might think of with a (more
complicated) “WHERE” clause:

mysql> SELECT purchases.purchase_id, f_name, l_name, date
FROM purchases, clients WHERE
purchases.client_id=clients.client_id;
+-------------+---------+--------+------------+
+ + + + +
| purchase_id | f_name | l_name | date |
+-------------+---------+--------+------------+
| 1 | Russell | Martin | 2007 11 09 |
2007-11-09
| 2 | Russell | Martin | 2007-11-10 |
| 4 | Bob | Milnor | 2007-11-20 |
| 5 | Larry | Vance | 2007-11-20 |
2007 11 20
| 6 | Sarah | Ford | 2007-11-21 |
| 7 | Paul | Abbott | 2007-11-25 |
| 8 | Sarah | Ford | 2007-11-25 |
2007 11 25
+-------------+---------+--------+------------+

mysql>
۶۴

More Complex Queries (cont )
(cont.)
• Find the purchases by the person named “Ford”
“Ford”.

mysql> SELECT purchases.purchase_id, f_name, l_name, date
FROM purchases, clients
WHERE (purchases.client_id=clients.client_id) AND
(l_name='Ford');
+-------------+--------+--------+------------+
+ + + + +
+-------------+--------+--------+------------+
| 6 | Sarah | Ford | 2007-11-21 |
2007 11 21
| 8 | Sarah | Ford | 2007-11-25 |
+-------------+--------+--------+------------+

mysql>

۶۵

Querying multiple tables
• In addition, we can query many tables (i.e. more than two) at once:
• First we’ll find all the purchases by a person with ll_name= Martin .
we ll name=‘Martin’

mysql> select p
y q purchases.purchase_id, f_name, l_name, date FROM
p , , ,
purchases, clients WHERE
(purchases.client_id=clients.client_id) AND (l_name='Martin')
ORDER BY purchases.purchase_id;
+-------------+---------+--------+------------+
+-------------+---------+--------+------------+
| 1 | Russell | Martin | 2007-11-09 |
| 2 | Russell | Martin | 2007-11-10 |
+-------------+---------+--------+------------+

mysql>

۶۶

Querying multiple tables (cont.)
• Now let’s find out the items (the “book_id”) in each purchase:

mysql> SELECT purchases.purchase_id, f
l> h h id f_name, ll_name, d t
date,
itemlist.book_id FROM purchases, clients, itemlist
(l_name='Martin') AND
(purchases.purchase_id=itemlist.purchase_id)
(purchases purchase id=itemlist purchase id)
+-------------+---------+--------+------------+---------+
| purchase_id | f_name | l_name | date | book_id |
+-------------+---------+--------+------------+---------+
| 1 | Russell | Martin | 2007-11-09 | 2 |
| 1 | Russell | Martin | 2007-11-09 | 6 |
| 1 | Russell | Martin | 2007-11-09 | 3 |
| 2 | Russell | Martin | 2007-11-10 | 5 |
| 2 | Russell | Martin | 2007-11-10 | 4 |
+-------------+---------+--------+------------+---------+


mysql>

۶٧

• Finally we can find the actual book titles by querying all four tables at
once:
mysql> SELECT purchases.purchase_id, f_name, l_name, date,
itemlist.book_id, title
FROM purchases clients itemlist, books
purchases, clients, itemlist
(purchases.purchase_id=itemlist.purchase_id) AND
(itemlist.book_id books.book_id)
(itemlist book id=books book id)
+-------------+---------+--------+------------+---------+------------------+
| purchase_id | f_name | l_name | date | book_id | title |
+-------------+---------+--------+------------+---------+------------------+
| 1 | Russell | Martin | 2007-11-09 | 6 | Blackbeard |
| 1 | Russell | Martin | 2007-11-09 | 2 | Learning SQL |
| 1 | Russell | Martin | 2007-11-09 | 3 | Abstract Algebra |
| 2 | Russell | Martin | 2007-11-10 | 4 | Rising Sun |
| 2 | Russell | Martin | 2007-11-10 |
2007 11 10 5 | Round the Moon |
+-------------+---------+--------+------------+---------+------------------+

mysql>

۶٨

Using aliases in queries
• Especially long queries might benefit from the SQL capability for
using aliases.
mysql> select p.purchase_id, title FROM purchases AS p, clients
AS c, itemlist AS i, books WHERE (p.client_id=c.client_id) AND
(l_name='Martin') AND (p.purchase_id=i.purchase_id) AND
(i.book_id books.book_id)
(i.book id=books.book id) ORDER BY p.purchase id;
p.purchase_id;
+-------------+------------------+
| purchase_id | title |
+-------------+------------------+
| 1 | Blackbeard |
| 1 | Learning SQL |
| 1 | Abstract Algebra |
| 2 | Rising Sun |
| 2 | Round the Moon |
+-------------+------------------+

An alias uses the SQL keyword ‘AS’ to associate a new identifier with a
table. It should appear after the table name and before the alias.
Once a table is aliased you must use that alias everywhere iin th
O t bl i li d t th t li h the
٧٠
SQL query.

Searching tables
The SQL “wildcard” character is the % symbol That is it can literally represent
wildcard symbol. is,
anything. Using it we can build searches like the following:
mysql> SELECT * FROM clients WHERE l_name LIKE '%a%';
+-----------+---------+--------+--------------------------+----------------+----------+
+ + + + + + +
+-----------+---------+--------+--------------------------+----------------+----------+
| 1 | Russell | Martin | Dept of Computer Science | Liverpool | L69 3BX |
+-----------+---------+--------+--------------------------+----------------+----------+

This above search finds all data that has a letter “a” in the user_id column.
mysql> SELECT * FROM clients where l_name LIKE '%an%';
+-----------+--------+--------+---------------+-----------+----------+
+-----------+--------+--------+---------------+-----------+----------+
+-----------+--------+--------+---------------+-----------+----------+

٧١

More on PHP and SQL
To increase security of your PHP/SQL setup (and to make it easier to change the
database you use), it’s recommended that you build an “include” file that will have
use) it s include
the information you use to connect to the database.

<?php
/* Save this as db_login.php (or whatever you like) and include it
in your php script. */

// Here’s the information to connect to the database.
$db_host = ‘mysql’;
$db_database=‘martin’;
$db_username= martin ;
$db username=‘martin’;
$db_password=‘’;
?>

If someone tries to view this file through their browser, the PHP interpreter will process
it and return a blank page to the user (there’s no HTML in the file).

٧٣

Connecting to the database
g
Now you can build your PHP script as follows (using the commands that we discussed
previously):

<?php
require_once (‘db_login.php’);

$connection = mysql_connect($db_host, $db_username, $db_password);

if (!$connection) /* check if the connection was actually successful */
{
exit(“Could not connect to the database: <br/>” .
htmlspecialchars(mysql_error()) );
}
else {
// more statements here. . .
}
?>

Note: The function ‘htmlspecialchars()’ converts special characters in a string into their
HTML escape sequences (like ‘&’ into ‘&’ and so forth).
This can also be used to increase the security of your code by and help thwart attacks
on your database by passing it information that your client has submitted before trying
٧۴ to insert it in your database.

MySQL queries inside of PHP
Your mySQL queries from a PHP script are the same as they are as when you’re using the
mySQL program from the command line with one difference… the queries do not have
a semi-colon at the end.
Aside f
A id from this difference, all of the regular SQL commands and k
thi diff ll f th l d d keywords are available
d il bl
when you perform your queries.

You
Y can create new t bl alter, and d l t th from inside of a PHP script, and you can
t tables, lt d delete them f i id f i t d
also insert and delete rows of tables as normal too. For any such operation, you’ll
likely want to check to see if it’s successful (especially if you’re trying to insert into or
extract data from the database).

<?php
// Assuming a valid database connection has been established.
// Build the query string by assigning variables...
$query = $select . $column . $from . $tables . $where;
$result = mysql_query($query);
if(!$result) {
exit(“Could not query the database: <br/>” .
/
htmlspecialchars(mysql_error()) );
}
else {
// process the data
}
?>
٧۵

Processing the results of a query

• There
Th are two main PHP methods to f h the results of an SQL query, these b i
i h d fetch h l f h being
‘mysql_fetch_row()’ and ‘mysql_fetch_array()’.

<?php
// Assuming a database connection, and a valid query string.
$result = mysql_query( $query );
while ($result_row = mysql_fetch_row($result)) {
echo $result_row[2] . ‘<br/>’;
}

?>

The ‘mysql fetch row()’ command fetches the query results as an enumerated array
mysql_fetch_row()
(an array that uses numerical indices), one row at a time, returning FALSE when
there are no more rows (ending the ‘while’ loop in this case).

٧۶

Processing the results of a query (cont.)
• mysql_fetch_array can get a row of results as an associative array (using
strings as the array indices) It takes a result as its first parameter and an optional
indices). parameter,
second parameter as a way to bind the results in the array.
• If MYSQL_ASSOC is specified, the results are indexed using the column names in
the query. If MYSQL_NUM is specified, then the numerical array indices (starting
query MYSQL NUM specified
at zero) access the results. The default value MYSQL_BOTH returns an array with
both types.
while ( $row = mysql_fetch_array($result, MYSQL_ASSOC) ) {
echo $row[“title”] . ‘<br/>’;
}

• Using a statement like ‘mysql_fetch_array($result, MYSQL_NUM)’ is essentially
equivalent to the statement ‘mysql_fetch_row($result)’ as they both return arrays
stored with numerical indices
indices.
• The ‘mysql_fetch_array()’ command can be used to save memory by specifying,
say, MYSQL_ASSOC, instead of the default value.

٧٧

Other useful PHP/SQL related functions

• The f
Th function ‘mysql_data_seek($result, $ l )’ can b used to move the iinternall
i ‘ l d k($ l $value)’ be d h
result pointer (which is advanced automatically when commands like
‘mysql_fetch_array()’ is called). This allows you, for example, to reprocess the
results of a query (without having to access the database again).
‘mysql_data_seek($result, 0);’ will reset the pointer to the initial row in the query
result (but is an error if the query result was empty).
( q y p y)

• ‘mysql_num_rows ($result);’ returns the number of rows in the query result.

• ‘mysql_affected_rows();’ gives the number of affected rows by the last INSERT,
DELETE, UPDATE
DELETE UPDATE, or REPLACE query. query

• ‘mysql_insert_id();’ returns the ID generated by the AUTO_INCREMENT of the
most recent query if there was one, or ‘0’ if there was no AUTO_INCREMENT
٧٨ value.

Lecture8

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Lecture8