CS计算机代考程序代写 Java javascript asp.net SQL database python Intro to PHP & MySQL

程序代写 CS代考 / asp.net, database, javascript, Java代写代考, Python代写代考, SQL代写代考

Intro to PHP & MySQL
2020/21 COMP3322 Modern Technologies on WWW

Contents
• Server-side Technologies
• A quick tour of PHP
• Common server-side scripting scenarios • Intro to MySQL
• Session & Cookie
2

Server-side Scripting
• “Server-side scripting is a technique used in web development which involves employing scripts on a web server which produce a response customized for each client’s request to the website.” – from Wikipedia.
• Customized means dynamically generating content.
3

Common Server-side Technologies
• PHP
• Python
• Django • Ruby
• Ruby on Rails • ASP.NET
• Node.js
• Perl
https://www.similartech.com/categories
4

History of PHP development
• PHP is an open source technology and runs on most operating systems and with most Web servers.
• It takes most of its syntax from C, Java, and Perl.
• PHP was written in the C programming language by Rasmus Lerdorf in 1994.
• For managing his person information. For this reason, PHP originally stood for “Personal Home Page”.
• Rasmus released PHP 1.0 in 1995; he extended it to work with web forms and databases.
• A development team began to form and PHP 2 was released in late 1997.
• The acronym was formally changed to PHP: HyperText Preprocessor since then.
• PHP 3 was released in 1998 and PHP 4 was released in 2000.
• PHP 5 was released in 2004 and the latest PHP version is 7, which was released in 2015.
5

A Quick Tour of PHP

PHP: Hypertext Preprocessor
• PHP, like JavaScript, is a dynamically typed language.
• It uses classes and functions in a way consistent with other object-
oriented languages such as C++, C#, and Java.
• The syntax for loops, conditionals, and assignment is identical to JavaScript.
• Differs when you get to functions, classes, and in how you define variables.
7

PHP Tags
• The most important fact about PHP is that the programming code can be embedded directly within an HTML file.
• A PHP file will usually have the extension .php
• Programming code must be contained within
• an opening tag
• Any code outside the tags is echoed directly out to the client
• Onserverswithshorthandsupport,aPHPscriptcanstartwith
8

PHP Tags

“Tony”;



Example 1

Welcome

Current server time is



echo ““;
echo date(“H:i:s”);
echo ““;
?>



Example 1

Welcome Tony

Current server time is 09:38:54



9

PHP Comments

10

Variables
• Variables in PHP are loosely typed in that a variable can be assigned different data types over time.
• Similar to JavaScript
• To declare a variable you must preface the variable name with the dollar
($) symbol.
• $count = 42;
• A variable name must start with a letter or the underscore character.
• A variable name can only contain alpha-numeric characters and
underscores (A-z, 0-9, and _ )
• Variable names are case-sensitive.
11

Variable Scope
• PHP has three different variable scopes: • Local scope
• Global scope • Static scope
• Local Scope
• A variable declared in a function can be referenced solely in that function.

12

Variable Scope
• Global Scope
• A variable defined in the main script (outside a function) has a GLOBAL SCOPE and can only be accessed outside a function.
• PHP does allow variables with global scope to be accessed within a function using the global keyword

13

Variable Scope

• Static Scope
• When a function is completed, all of its variables
are deleted.
• A static variable exists only in a local function scope, but it does not lose its value when program execution leaves this scope.
• A static variable is initialized only in first call of the function.
14

Writing Output
• To output something that will be seen by the browser, you can use the echo() or print() function.
• echo(“hello”); or echo “hello”; OR • print(“hello”); or print “hello”;
• Output variables • echo $name;
• Another alternative is using the printf() function.
• Like the C programming language; also have the variations like sprintf() and
fprintf().
• printf(“

%s

\n”, $title);
https://www.w3schools.com/php/func_string_printf.asp
15

$course = array(
“code” => “COMP3322”,
“title” => “Modern Tech on WWW”, “sem” => 2,
“class” => “B”,
“teacher” => array(“last” => “Tam”,
“first” => “Anthony”));
Writing Output
• Debugging
• var_dump(), var_export(), and print_r() are functions that you can use to check values.
• var_dump() shows the values and their types of a variable. Arrays and objects are explored recursively with values indented to show structure.
• print_r() only shows the value in a human- readable format.
• var_export() like the above two, but it returns the information in a parsable string representation.
var_dump($course); array(5) {
[“code”]=>
string(8) “COMP3322” [“title”]=>
string(18) “Modern Tech on WWW” [“sem”]=>
int(2)
[“class”]=>
string(1) “B”
[“teacher”]=>
array(2) {
[“last”]=> string(3) “Tam” [“first”]=> string(7) “Anthony”
} }
print_r($course); Array
(
[code] => COMP3322
[title] => Modern Tech on WWW [sem] => 2
[class] => B
[teacher] => Array
(
[last] => Tam
[first] => Anthony )
) 16

“COMP3322”,
“title” => “Modern Tech on WWW”, “sem” => 2,
“class” => “B”,
“teacher” => array(“last” => “Tam”,
“first” => “Anthony”));
echo “output by ‘var_dump’
“; var_dump($course);
echo “
output by ‘print_r’
“; print_r($course);
echo “
output by ‘var_export’
“; var_export($course);
?>

Welcome to

Current server time is “;
echo date(“H:i:s”);
echo ““;
?>


https://i.cs.hku.hk/~atctam/c3322/PHP/debug.php
17

Data Types
Data Type
Description
boolean
A logical true or false value
integer
Whole numbers
Max. size is platform-dependent, but at least 32-bit.
float
Decimal numbers
Again platform-dependent; usually, in 64 bit IEEE format.
string
A sequence of characters (8 bits) enclosed in single or double quotes.
Array
An array in PHP is actually an ordered map.
It supports numeric array, associative array, and multi- dimensional array.
Object
Instances of programmer-defined classes.
Null
NULL is the only possible value of type null.
18

Case Sensitivity
• Case sensitive • variables
• constants
• array keys
• class properties
• Case insensitive • functions
• class constructors/methods
• keywords and constructs (e.g., if, else, echo, etc.)
19

Constants
define(“DB_HOST”, “localhost”); define(“DB_NAME”, “StudentDB”); define(“USERNAME”, “c3322”); define(“PASSWORD”, “ew#@rtycd”);
$db = mysqli_connect(DB_HOST, USERNAME, PASSWORD, DB_NAME); • Define the constant via the define() function
• Once a constant is defined, it can be referenced without using the $ symbol.
20

String
• A string can be any text inside quotes. You can use single or double quotes.
• String Concatenation
• Strings can easily be appended together using the concatenate operator,
which is the period (.) symbol.
• Alert! JavaScript uses the plus (+) symbol.
• Example:
• $username = “World”;
• echo”Hello”.$username; • WillOutput“HelloWorld”
21

String
• Difference between single quote and double quote strings. • Single quotes are used to denote a “literal string”.
• The system does not attempt to parse special characters or variables within the single quote string.
• You can add special characters (e.g., \n, \t) and variables in double quote string. The system understands.
• Example:
$username = “World”; echo “Hello $username”; Will Output “Hello World”
$username = “World”;
echo ‘Hello $username’; Will Output “Hello $username”
22

Arrays
• Defining an array
• $days = array();
• Thisdeclaresanemptyarray.
• You can initialize it with a comma-delimited list of values using either of two following syntaxes:
• $days = array(“Mon”,”Tue”,”Wed”,”Thu”,”Fri”); • $days = [“Mon”,”Tue”,”Wed”,”Thu”,”Fri”];
• You can also declare each subsequent element in the array individually: • $days = array();
• $days[0] = “Mon”;
• $days[1] = “Tue”;
• $days[] = “Wed”;
23

Arrays
• In most programming languages array keys are limited to integers, start at 0, and go up by 1.
• In PHP, array keys must be either integers or strings and need not be sequential.
• If you don’t explicitly define the keys, they are 0,1,…
• Fornumericindexes,youcanskipsomeindexes. • $menu[0] = “appetizer”;
• $menu[2] = “soup”;
• $menu[4] = “main course”; • $menu[8] = “dessert”;
• print_r($menu);
//Array([0] => appetizer [2] => soup [4] => main course [8] => dessert)
24

Arrays
• Associative Arrays
• $record = array(“name” => “Tony Stark”, “number” =>
“3015123456”, “age” => 20, “email” => “tonystark@hku.hk”);
• $record = [“name” => “Tony Stark”, “number” => “3015123456”, “age” => 20, “email” => “tonystark@hku.hk”];
• To loop through and print all the values of an associative array, we could use a foreach loop
foreach ($record as $x => $x_value) {
echo “Key=” . $x . “, Value=” . $x_value;
}
25

Superglobal Variables
• Superglobal
• Several predefined variables in PHP can always be accessible, regardless of scope.
• Commonly used superglobal variables are: • $_GET
• An associative array containing name/value pairs sent from the client with the GET method
• $_POST
• An associative array containing name/value pairs sent from the client with the POST method
• $_COOKIE
• An associative array containing cookie variables and values
• $_SESSION
• An associative array containing session
variables and values • $_REQUEST
• An associative array contains the contents of $_GET, $_POST and $_COOKIE
• $_SERVER
• An associative array contains information about request headers, paths, and script locations
https://www.w3schools.com/php/php_superglobals.asp
26

Include Files
• PHP provides four different statements for including files, as shown below.
• include “somefile.php”;
• include_once “somefile.php”; • require “somefile.php”;
• require_once “somefile.php”;
• The include and require statements are identical, except upon failure
• With include, a warning is displayed and then execution continues. With require, an error is displayed and execution stops.
27

The Scope of Include Files
• Include files are the equivalent of copying and pasting.
• Variables defined within an include file will have the scope of the
line on which the include occurs.
• Any variables available at that line in the calling file will be available within the called file.
• If the include occurs inside a function, then all of the code contained in the called file will behave as though it had been defined inside that function.
28

User Defined Functions in PHP
• A user-defined function declaration starts with the word function.
function functionName($arg1,$arg2,…..,$argX) { code to be executed;
}
• A function name must start with a letter or an underscore. Function names are NOT case-sensitive.
• Functions need not be defined before they are referenced.
• All functions in PHP have the global scope
• They can be called outside a function even if they were defined inside another function.
29
< ? < User-Defined Functions • Function parameters • These parameters work like variables inside your function; in principle, they are of dynamic type. • Since PHP 7, it is possible to declare types for the function parameters. • http://php.net/manual/en/functions.arguments.php#functions.arguments.type- declaration • PHP supports passing arguments by value (the default), passing by reference, and default argument values. • Pass by reference: function myFunction(&$arg) { . . . . } 30 Using JSON in PHP • PHP has some built-in functions to handle JSON. • Objects and arrays in PHP can be converted into JSON string by using: $json_str = json_encode($php_obj); $json_str = json_encode($php_arr); • Converting a JSON string into a PHP object or array by using: $anArray = json_decode($json_str, true); $anObject = json_decode($json_str); • In the event of a failure to decode, json_last_error() can be used to determine the exact nature of the error. When TRUE, returned objects will be converted into associative arrays. 31 decode() Breakfast at
Tiffany’s
}
$anObject = json_decode($json_str);
if (json_last_error() == JSON_ERROR_NONE) { echo $anObject->library->DVD[1]->title;
}
?>
//-> Contact
32

encode()
library->DVD[1]->title = “Avengers”;
$anObject->library->DVD[1]->genre = “Action”; $new_str = json_encode($anObject);
echo $new_str; ?>
//-> {“library”:{“DVD”:[{“id”:”1″,”title”:”Breakfast at Tiffany’s”,”format”:”Movie”,”genre”:”Classic”},{“id”:”2″,”title”:”Av engers”,”format”:”Movie”,”genre”:”Action”}]}}
33

Common Server-side Scripting Scenarios

Common Actions
Access data in the request
Perform the computation
• Validate the data
• Database accesses
Store/retrieve data
to/from database
• Compose the response
Keep state information
35

Demo 1 – Just Echo Back

Account Registration Form


: :

Account Registration Form


: :
36

Demo 1 – Just Echo Back
view1.php http://i7.cs.hku.hk/~atctam/c3322/PHP/form-php1.html
Name : “.$_GET[‘name’].”

“; echo “

No. : “.$_GET[‘number’].”

“; echo “

Age : “.$_GET[‘age’].”

“; echo “

Email: “.$_GET[’email’].”

“;
?>
view2.php http://i7.cs.hku.hk/~atctam/c3322/PHP/form-php2.html
Name : “.$_POST[‘name’].”

“; echo “

No. : “.$_POST[‘number’].”

“; echo “

Age : “.$_POST[‘age’].”

“; echo “

Email: “.$_POST[’email’].”

“;
?>

Demo 1 – Just echo back

Name : James Bond

No. : 3015007007

Age : 27

Email: jamesbond@hku.hk


37

Demo 2 – List All Records

Account Registration Form


: :
38

http://i7.cs.hku.hk/~atctam/c3322/PHP/form-php3.html
Demo 2 – List All Records
Name : “.$Std_record[$i][‘name’].”
“; echo “No. : “.$Std_record[$i][‘number’].”
“; echo “Age : “.$Std_record[$i][‘age’].”
“; echo “Email: “.$Std_record[$i][’email’].”

“;
}
#Add the new record to the array
$record[‘name’]=$_POST[‘name’]; $record[‘number’]=$_POST[‘number’]; $record[‘age’]=intval($_POST[‘age’]); $record[’email’]=$_POST[’email’]; $Std_record[3]=$record;
?>
39

Intro to MySQL

Demo 4 – Retrieve Records From DB

Account Registration Form


: :
http://i7.cs.hku.hk/~atctam/c3322/PHP/form-php5.html
41

Demo 4 – Retrieve Records From DB
0) {
while ($row=mysqli_fetch_array($Std_record)) {
?>
echo echo echo echo
}
} else {
echo “

No record!!

“; }
mysqli_free_result($Std_record); mysqli_close($db_conn);
“

Name : “.$row[‘stdName’].”
“; “No. : “.$row[‘stdNumber’].”
“; “Age : “.$row[‘stdAge’].”
“; “Email: “.$row[‘stdEmail’].”

“;
42

PHP Database Support
• PHP supports many databases
• MySQL, MongoDB, IBM DB2, Mssql, Ingres, PostgreSQL, etc.
• MySQL is the most popular database system used with PHP. • MySQL uses standard SQL
• MySQL is very fast, reliable, and easy to use • MySQL compiles on a number of platforms
• To have a quick overview on PHP + MySQL, please visit: https://www.w3schools.com/php/php_mysql_intro.asp
43

Database Design
• A database in a Relational DBMS is composed of one or more tables.
• A table is a two-dimensional container for data that consists of records (rows);
• Each record has the same number of columns, which are called fields, which contain the actual data.
• Each table will have one special field called a primary key that is used to uniquely identify each record in a table.
44

Database of Demo 4
Primary key field
stdName stdNumber stdAge stdEmail
Tony Stark 3015111111 27 tonystark@hku.hk
Field names Record
Peter Parker
Bruce Banner
3015222222 24
3015333333 21
peterparker@hku.hk
brucebanner@hku.hk
45

phpMyAdmin
https://i.cs.hku.hk/phpmyadmin/index.php
How should I apply for a MySQL database account?
Each user may apply for a MySQL database account using the online form at https://intranet.cs.hku.hk/common/mysqlacct/
46

Create Table
• The CREATE TABLE statement is used to create a new table in a database.
CREATE TABLE stdRecord(
stdName VARCHAR(50) NOT NULL, stdNumber VARCHAR(10) NOT NULL, stdAge TINYINT(3),
stdEmail VARCHAR(50) NOT NULL, PRIMARY KEY(stdNumber)
);
47

Insert Records
• Insert rows into the table.
INSERT INTO stdRecord (stdName, stdNumber, stdAge, stdEmail) VALUES (“Tony Stark”, “3015111111”, 27, “tonystark@hku.hk”);
INSERT INTO stdRecord (stdName, stdNumber, stdAge, stdEmail) VALUES (“Peter Parker”, “3015222222”, 24, “peterparker@hku.hk”);
INSERT INTO stdRecord (stdName, stdNumber, stdAge, stdEmail) VALUES (“Bruce Banner”, “3015333333”, 21, “brucebanner@hku.hk”);
48

SELECT
• The SELECT statement is used to retrieve data from the database.
• The result of a SELECT statement is a block of data typically called a
result set.
• You must specify
• which fields to retrieve and • which Table to retrieve from
49

SELECT
SELECT * FROM stdRecord;
50

SELECT
SELECT * FROM stdRecord WHERE stdNumber = “3015222222”;
51

SELECT
SELECT stdName, stdEmail FROM stdRecord WHERE stdNumber = “3015222222”;
52

Accessing MySQl in PHP
1. Connect to the database.
2. Handle connection errors.
3. ExecutetheSQLquery.
4. Processtheresults.
5. Free resources and close connection.
53

Connect to the database
mysqli_connect(“db server”, “username”, “password”, “database”)
Demo 4
0) {
while ($row=mysqli_fetch_array($Std_record)) {
Handle connection errors mysqli_connect_error( )
“

Name : “.$row[‘stdName’].”
“; “No. : “.$row[‘stdNumber’].”
“; “Age : “.$row[‘stdAge’].”
“; “Email: “.$row[‘stdEmail’].”

“;
echo
echo
echo
echo
}
} else {
echo “

No record!!

“; }
54
die(“error message”)

• The mysqli_connect() function opens a new connection to the MySQL server.
• Returns the connection object to the MySQL server. mysqli_connect(host,username,password,dbname,port,socket);
host Optional. Specifies a host name or an IP address
username Optional. Specifies the MySQL username
password Optional. Specifies the MySQL password
dbname Optional. Specifies the default database to be used
port Optional. Specifies the port number.
socket Optional. Specifies the socket.
• The mysqli_connect_error() function returns the error description from the last connection error.
mysqli_connect_error();
• The die() function prints a message and exits the current script. die(message);
Connection Error! Access denied for user ‘c3322a’@’i1.cs.hku.hk’ (using password: NO)
55

Execute the SQL query
mysqli_query(“db connection”, “query string”)
Demo 4
0) {
while ($row=mysqli_fetch_array($Std_record)) {
“

Name : “.$row[‘stdName’].”
“; “No. : “.$row[‘stdNumber’].”
“; “Age : “.$row[‘stdAge’].”
“; “Email: “.$row[‘stdEmail’].”

“;
echo
echo
echo
echo
}
} else {
echo “

No record!!

“; }
56
Handle errors mysqli_error(“db connection” )
Process the results mysqli_num_rows(“ return result set” )
Process the results mysqli_fetch_array(“ return result set” )

• The mysqli_query() function performs a query against the database.
• For successful SELECT, SHOW, DESCRIBE, or EXPLAIN queries it will return a mysqli_result object. For other successful queries it will return TRUE. FALSE on failure.
mysqli_query(connection,query,resultmode);
connection Required. Specifies the MySQL connection to use
query Required. Specifies the query string
resultmode Optional. Either:
* MYSQLI_STORE_RESULT [default]
* MYSQLI_USE_RESULT (Use unbuffered query; use this if we have to retrieve large amount of data)
• The mysqli_error() function returns the last error description for the most recent function call.
mysqli_error(connection);
57

• The mysqli_num_rows() function returns the number of rows in a result set.
mysqli_num_rows(result);
• The mysqli_fetch_array() function fetches a result row as an associative array, a numeric array, or both.
• Returns an array of strings that corresponds to the fetched row. NULL if there are no more rows in result-set.
mysqli_fetch_array(result,resulttype=MYSQLI_BOTH);
result
Specifies a result set identifier returned by mysqli_query().
result
Specifies a result set identifier returned by mysqli_query().
resulttype
Optional. Specifies what type of array that should be produced. Can be one of the following values: MYSQLI_ASSOC, MYSQLI_NUM, or MYSQLI_BOTH
58

• How about fetching all result rows in one call?
• The mysqli_fetch_all() function fetches all result rows and returns
the result-set as an associative array, a numeric array, or both.
• Returns an array of associative or numeric arrays holding the result rows
mysqli_fetch_all(result,resulttype=MYSQLI_NUM);
result
Specifies a result set identifier returned by mysqli_query().
resulttype
Optional. Specifies what type of array that should be produced. Can be one of the following values: MYSQLI_ASSOC, MYSQLI_NUM, or MYSQLI_BOTH
• Good for directly converting the result array to JSON data
59

Demo 4
0) {
while ($row=mysqli_fetch_array($Std_record)) {
echo echo echo echo
}
} else {
echo “

No record!!

“; }
mysqli_free_result($Std_record); mysqli_close($db_conn);
“

Name : “.$row[‘stdName’].”
“; “No. : “.$row[‘stdNumber’].”
“; “Age : “.$row[‘stdAge’].”
“; “Email: “.$row[‘stdEmail’].”

“;
?>
60
Free resources and close connection mysqli_free_result(“result set” )
Free resources and close connection mysqli_close(“db connection” )

Demo 5 – Check Duplication Before INSERT

Account Registration Form


: :
61

Demo 5 – Check Duplication Before INSERT

Account Registration Form


: :
http://i7.cs.hku.hk/~atctam/c3322/PHP/form-php6.html
62

Demo 5
Query Error!
“.mysqli_error($db_conn).”

“);
if (mysqli_num_rows($result) > 0) {
echo “

Duplicated record

“;
echo “

The student with Student No.: “.$num.” is already existed in the database.”;
} else { :
:
Execute the SQL query. Process the results.
63

Demo 5
:
} else {
$query=”INSERT INTO stdRecord (stdName, stdNumber, stdAge, stdEmail) VALUES (‘$name’, ‘$num’, ‘$age’, ‘$email’)”;
if (!mysqli_query($db_conn, $query)) {
echo “

Error insert!!
“.mysqli_error($db_conn).”

“;
}
#Retrieve all records from DB
$query=”SELECT * FROM stdRecord”; $Std_record=mysqli_query($db_conn, $query)
or die(“

Query Error!
“.mysqli_error($db_conn).”

“);
#Display the records
if (mysqli_num_rows($Std_record) > 0) { :
:
:
Execute the SQL query. Process the results.
64

Session & Cookie

Cookies
• Cookies are the key/value (variable/value) pairs maintained by browsers.
• How cookie works:
• When receiving an HTTP request, the server sends a Set-Cookie header with
the response.
• Browser stores the cookie.
• With future requests made to the same server, the browser sends the cookies in the request in a Cookie HTTP header.
• An expiration date or duration can be specified, after which the cookie is no longer sent.
• Restrictions to a specific domain and path can be set, limiting where the cookie is sent.
66

setcookie ( string $name
[, string $value = “” [, int $expires = 0
[, string $path = “” [, string $domain = “”
[, bool $secure = FALSE [, bool $httponly = FALSE ]]]]]] )
PHP Cookies
• A cookie is created with the setcookie() function. setcookie(name, value, expire, path, domain, secure, httponly);
name
The cookie name.
value
Optional. Specifies the value.
expire
Optional. Specifies the time the cookie expires.
path
Optional. Specifies the directories for which the cookie is valid.
domain
Optional. Specifies the domain name for which the cookie is valid.
secure
Optional. Specifies whether carries by HTTPS or HTTP.
httponly
Optional. Limits only to HTTP protocol; JavaScript cannot access it.
• Retrieve the value of a cookie using the superglobal variable $_COOKIE.
• Use the isset() function to find out if the cookie is set.
• To delete a cookie variable, just use setcookie() function to set the cookie expiration time to be anytime in the past.
67



Setting Cookies with PHP

Access page

Access inner page

Clear cookies


Demo 6 – cook-01.php
68

Demo 6 – cook-02.php
cook-02.php


Accessing Cookies with PHP

“;
} else {
echo “Cookie userid is not set\n”;
}
?>

“;
} else {
echo “Cookie page is not set\n”;
}
?>


inner/cook-02.php

69



Delete Cookies with PHP

Has cleaned all cookies.


Demo 6 – cook-03.php
70

Sessions
• Server-side Cookies
• A session is a methods of storing data (using variables) on the server and
the data will be available to all pages on the site during that visit. • How session works:
• Once connected, server sends a cookie that contains the session ID to the browser.
• In the subsequent requests, the browser sends the session ID cookie (together with other cookies from this site) to the server.
• PHP can retrieve the data based on the session ID and make the data available in your PHP script.
• The session ends once the window or tab in which the webpage was loaded, is closed or the server explicitly destroys all session variables.
71

Open a New Session
• A session is started with the session_start() function.
• This function first checks if a session is already started and if none is
started then it starts a new session.
• If a new session is started, a cryptographic session ID is created.
• Session data is stored on the server in text file or even database.
• The session ID is associated with saved session data, in this way
providing a method for tying a particular user to this data.
• Important Note:
• The session_start() function must be the very first thing in your PHP file before any HTML tags.
• AllPHPfilesmustincludethesession_start()functiontoaccessthesessiondata.
72

Propagation of Session ID
• There are two methods to propagate a session ID: • Cookie [default]
• Send the session ID to the browser in form of a cookie named PHPSESSID. • PHPSESSID=9hjtvg980cakoblsloa4mag75u
• URL parameter
• Propagated by the URL as part of the query string
•
• PHP is capable of transforming links transparently. If the run-time option session.use_trans_sid is enabled, relative URLs will be changed to contain the session id automatically.
• Session IDs are propagated across different HTTP requests by cookies or by appending to each URL as query string.
73

Access Session Data
• Session data can be accessed via the $_SESSION superglobal array variable.
• Use a session variable (no declarations needed). • $_SESSION[“something”]=”somevalue”;
• Use isset() to check whether a session variable is set.
• Use unset() to remove a session variable.
• To free all session variables, use session_unset().
• To destroy all of the data associated with the current session that is stored in the session storage, use session_destroy().
• To remove session cookie, use setcookie() to set the session ID to expire.
74

Demo 7 – login.php
Before log on
or Fail authentication After authenticated
after log out
75

Demo 7
Get session data

Login






Welcome

Welcome to the member area!

logout

delete cookie
if (isset($_COOKIE[session_name()])) { setcookie(session_name(),”,time()-3600, ‘/’);
}
session_unset(); session_destroy();
}
?>
#Set redirection
header(‘location: login.php’);
81

References
• PHP Tutorial – Tutorialspoint.com
• https://www.tutorialspoint.com/php/index.
htm
• PHP 5 Tutorial – W3school.com
• https://www.w3schools.com/php/default.as
p
• PHP Manual
• https://secure.php.net/manual/en/index.php
• PHP The Right Way
• https://phptherightway.com/
• PHP MySQL – W3school.com
• https://www.w3schools.com/php/php_mys
ql_intro.asp
• PHP Session – zentut.com
• http://www.zentut.com/php-tutorial/php- session/
82

Related Posts