building an online bidding application using php

8/6/2019 Building an Online Bidding Application Using PHP

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Building an online bidding

application using PHP/MySQL


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Introduction

Purpose of this lecture is to show how tobuild an online application using PHP/

MySQL platform This lecture is intended for developerswho wish to develop web-basedapplication but not familiar with PHP

syntaxes


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Online bidding application

Application is an online auction systemwhere items for bid are displayed to

browsers Interested browsers create/ log-in to theiraccount

Once logged-in, bidders can submit bidsfor items that are auctioned


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Outline

PHP basics MySQL connection Creation of accounts

Managing logins Adding bid items Deleting bid items Logging out

Viewing bid items Accepting bids Listing bids for each bid item


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Outline Topic #1 PHP Basics


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PHP basics

Background

Web application architecture

Basic syntax tags

Variables

O

perators Flow Control and Looping


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PHP basics-background

Server-side scripting language for the web

PHP codes are embedded in HTML todynamically generate web pages

Originally stood for Personal Home Page

Changed to PHP Hypertext Processor

Database integration

MySQL, PostgreSQL, etc Portability

Run on Linux, UNIX, Windows, MacOS platforms


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PHP basics-web application

architecture

To open a web page in browser: Type in a Universal Resource Locator (URL)

Click an existing link A request is sent to the web server

Web server locates the page and sends it back to the browser

Browser displays the page


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PHP basics-web application

architecture model Three Tiered Model Presentation Layer

Web browser- displays and submits the data

Application Layer Some programs or scripts which processes the data

PHP, JSP, Servlets, ASP,CGI, etc.

Database Layer

Provides the data that the application layer needs May be an RDBMS, a flat file, XML documents, etc.


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PHP basics- tags

Tells web server where PHP code ends

Code in between are processed

Ex:


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PHP basics- tags, an example

The code below outputs 10 + 15 = 25


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PHP basics- variables

No need to declare variables

Must start with dollar sign ($)

Values are assigned to variables by theassignment operator =

$name=Jun Dolor;

$qty=100;


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PHP basics- operators

String

Arithmetic

Assignment Comparison

Logical


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PHP basics- operators, string

Concatenation

. appends strings


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PHP basics- operators, arithmetic

+ addition

- subtraction

* multiplication / division

% modulus


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PHP basics- operators, arithmetic

Operator Use Equivalent to

+= $a += $b; $a= $a + $b;

-= $a -= $b; $a = $a - $b;

*= $a *= $b; $a = $a * $b;

/= $a /= $b; $a = $a / $b;

%= $a %= $b; $a = $a % $b;

.= $a .= $b; $a = $a . $b;


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PHP basics- operators, comparison

Operator Name Example

== Equals $a == $b

=== Identical $a === $b

!= Not equal $a != $b

Not equal $a $b

< Less than $a < $b

> Greater than $a > $b

= $b


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PHP basics- operators, logical

Operator Name Use Result

! NOT !$b Returns true if $b is falseand vice-versa

&& AND $a && $b Returns true if both $a and$b are true, otherwise false

|| OR $a || $b Returns true if either $a or $b is true, otherwise false

and AND $a and $b Same as &&, but with lower precedence

or OR $a or $b Same as ||, but with lower precedence


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PHP basics-arrays

Arrays are special type of variables forstoring a list of data and manipulatingthem efficiently

An array stores multiple data items,divided into a number of slots


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PHP basics-initializing numericallyindexed arrays

Initialization by direct assignment

Initialization by array construct

Array elements can be of different types


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PHP basics-initializing numericallyindexed arrays 2

Arrays are usually assigned sequentially

In PHP, arrays can be assigned non-sequentially


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PHP basics-using numericallyindexed arrays

To access an array element, or part of an array,use a number called index or subscript

Index number or subscript

Assigned to each member of the array to allow theprogram to access an individual member of the array

Usually begins with zero and progress sequentially bywhole numbers to the end of the array

NOTE: Elements inside arrays are from 0 tp(sizeOfArray 1)


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PHP basics-using numericallyindexed arrays 2

Accessing a single element

Accessing elements of an array using a for

loop

Accessing elements of an array using

foreach loop


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PHP basics-initializing string-indexed arrays

Initialization by direct assignment

Initialization by array construct

Accessing a single element


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PHP basics-initializing string-indexed arrays 2

Accessing elements of a string-indexedarray using list()/ each()


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PHP basics-each()

Receives an array as a parameter

Returns the current key and value pair as anarray with four elements

If the internal pointer for the array past the endof the array contents, each() returns FALSE

Moves the array pointer to the next element

Use reset() to move the array back at the firstelement


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PHP basics-each() 2


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PHP basics-list()

Used to assign multiple variables in oneoperation

Usually used to capture values returned byeach()


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PHP basics-foreach()

Gives an easy way to iterate over arrays

On sample code below:

For each loop, the value of the current element is

assigned to $value Internal array pointer is advanced by one

On the next loop, the next element is referenced


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PHP basics-foreach() 2

On the sample code below:

The current elements key will be assigned to thevariable $k on each loop


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PHP basics- multi-dimensionalarrays

PHP supports multi-dimensional arraysthrough array of arrays


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PHP basics- flow control andlooping

if

if-else

switch

for

while

do-while

break

exit or die


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PHP basics- if/ if-else statement

Statement- if:

A statement (or block of code) will executeonly if a certain boolean is true

Statement if-else

A statement (or block of code) will executeif a condition is true and a different

statement if the condition is false


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PHP basics- switch statement

Allows branching on multiple outcomes

When a switch is encountered: PHP evaluates expression and jumps to case whose

selector matches the value of the expression Program executes the statements in order from that

point on until a break statement is reached

This skips to the statement after the first statement atthe end of the switch

Should none of the case is satisfied, the default blockis executed

Default blocks are optional


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PHP basics- for loop

Executes the same code a number oftimes Syntax: for

(expression1;condition;expression2){statement/s} Where:

Expression1 is executed at the start; the counter isinitialized here

Condition is the test before each iteration Expression2 is evaluated at the end of each

iteration

Statement/s are executed once for each iteration


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PHP basics- while loop

Contains statements or block ofstatements to be repeated as long as thecondition is true

Syntax: while(condition){statement/s}

Statements inside the loop are executedfor as long as the condition take the true

value


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PHP basics- do while loop

Contains statement or block of statementsthat repeats as long as the condition istrue

Main difference between while and do-while loop:

Statements within a do-while loops executes

at least once

Syntax: do{statement/s}while(condition)


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PHP basics- break

Terminates the enclosed switch statementand flow of control transfers to the nextstatement after switch

This is also used to terminate for, whileand do-while loops


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PHP basics- exit or die

Stops the execution of the script with anoptional error message


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Outline Topic #2 MySQL

Connection


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MySQL Database Connection

Overview of database structure

Connecting to MySQL database

Selecting the database to use Using the require_once statement


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Overview of Database connection

Database: auction

Tables

tblaccount tblbiditems

tblbidhistory


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Table tblaccount

This will hold the account info of bidders/auctioneers

Table structure Column accountid: integer, primary key, auto-increment

Column username: string 50 chars

Columnpassword: string 50 chars


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Table tblbiditems

This will hold the items auctioned forbidding

Table structure Column biditemid: integer , primary key, auto-

increment

Column accountid: string 50 chars This identifies the auctioneer

Column biditem: string 50 chars

Column biddesc: tiny text


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Table tblbidhistory

This will hold the bid info for each itembeing auctioned

Table structure Column bidhistoryid: integer , primary key,

auto-increment

Column accountid: integer

Column biditemid: integer

Column bidprice: double

Column dtesubmitted: datetime


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Connecting to databases:

Function mysql_connect: Creates a connection to MySQL Syntax: mysql_connect($hostname,

$username,$password)

Ex: $conn=mysql_connect(localhost,root,password)

Function mysql_select_db Specifies the database in MySQL for use Syntax: mysql_select_db($database, $connection) Ex: mysql_select_db(auction, $conn)

Function die Terminates execution of PHP script


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Connecting to MySQL andselecting auction database

Create file dbconnect.inc

For code reuse, a separate file can be createdto connect to the database

PHP pages can call dbconnect.inc to connectyo the auction database


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Reusing the database connection

Function require_once()

Loads a file into a PHP script


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Outline Topic #3 Creation of

Accounts


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Creation of accounts

HTML form handling

MySQL commands

Function mysql_query() Function mysql_error()

Adding records

SQL insert statement


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HTML form handling

Create:

File index.html

File addaccount.html

File addaccountprocess.php

$_POST array


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File index.html

First page that displays

Provide the user with the option to create

accounts


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File addaccount.html

Displays a form for accepting new accountinfo


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File addaccountprocess.php

$_POST array Special arrays that hold all form variables

Function mysql_query() Executes an SQL statement on the database

Function mysql_error() Displays error encountered when executing

an SQL statement SQL Insert

Adds a record on a database table


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File addaccountprocess.php script


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Create accounts:

Username: auctioneer1

This account will place items for bidding

Usernames: bidder1, bidder2 These account will bid for item auctioned off


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Outline Topic #4 Managing Logins


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Managing logins

SQL select statement

Function mysql_num_rows

Function isset()

Session

URL rewriting Querystring

$_GET array

Create:

File login.php File loginverify.php

File checkstatus.inc

File menu.php


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SQL select statement

Example 1: select * from tblaccount Selects all columns/ rows from table tblaccount

Example 2: select username, password from tblaccount Selects columns username and password for all rows in table

tblaccount Example 3: select * from tblaccount where

username=jundolor Selects all columns from table tblaccount for all rows whose

column username contains jundolor

Example 4: select accountid from tblaccount whereusername=media Selects column accountid from tblaccount for all rows whose

column username contains media


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Function mysql_num_rows

Retrieves the number of rows from a resultset

Can only be used for SQL selectstatements


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Function isset()

Checks if a variable exist

Example: isset($name)

This check if the variable $name exist


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Sessions

Special variables stored in web servers

Allows passing of information betweenweb pages

Call the function session_start() at thestart of scripts that will use sessions


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URL Rewriting

Querystring

Information can be passed on by appendingvariable/value to the URL

$_GET array

Special array that holds all querystring values


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File login.php code


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File login.php browser shot


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File loginverify.php code


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File checkstatus.inc code


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File menu.php


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Outline Topic #5 Adding Items

to Auction


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Adding items to auction

File menu.php

Create:

File addauctionitem.php

File addauctionitemprocess.php


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File menu.php


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File addauctionitem.php code

Fil dd ti it h


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File addauctionitem.php screenshot


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File addauctionprocess.php


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Outline Topic #6 Deleting Bid

Items


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Deleting Bid Items

Function mysql_fetch_array()

Writing querystring URL to identify recordsto delete

SQL delete statement

Create:

File listauctionitems.php

File: deletebiditem.php


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Function mysql_fetch_array()

Fetches a row as an associative from aselect query result set


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Sample mysql_fetch_array() code

W iti t i URLt id tif


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Writing querystring URLto identifyrecords to delete

Auction items belonging to current accountwill be selected

A loop will be created to go through eachrow

Each row will hyperlink to a PHP basedpage for deletion

To identify the row, a querystring variablewill be appended to the URL

W iti t i URLt id tif


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Writing querystring URLto identifyrecords to delete- code


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SQL delete statement

Example 1: delete from tblaccount

Deletes all rows on table tblaccount

Example 2: delete from tblaccount whereaccountid=1

Deletes only rows matching the condition


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File menu.php


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File listauctionitems.php


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File deletebiditem.php


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Outline Topic #7 Logging Out


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Loggin out

Function session_destroy()

Create:

File logout.php


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Function session_destroy()

Terminates all session variables stored inserver memory


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File menu.php


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File logout.php

Once logout.php is called, all sessionvariable will be dropped from servermemory

Browser will not be able to access anypage calling checkverify.php (ex:menu.php)


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Outline Topic #8 Viewing Bid

Items


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Viewing bid items

Establishing relations between tables

SQL natural join clause

Create: File listbiditems.php


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Establishing relations

Table tblbiditem Holds the items being

auctioned off

Column accountid identifiesthe owner if the auctioned

item

Table tblaccount Holds account information

of the owner of the itembeing auctioned

Column accountid Links the owner of the

account to the auction item


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SQL natural join clause

Used with SQL select statement

Connects rows between different tablesvia their common column


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File menu.php


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File listbiditems.php

All items with their respective ownersbeing auction are listed

Each item will hyperlink to a PHP page for

accepting bids Accepting bids will be covered in the next

topic section

Each hyperlink will append a querystringvariable to identify it in the PHP page foraccepting bids


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File listbiditems.php code


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File listbiditems.php screen shot


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Outline Topic #9 Accepting

Bids


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Accepting bids

Using hidden fields to store ID numbers

MySQL now() function

Create:

File acceptbid.php

File acceptbidprocess.php


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Hidden fields

Not displayed to the browser

Used to pass constant values


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File acceptbid.php

Place the id of the auction item in a hidden field

Fil bid h h


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File acceptbid.php screen shot

File acceptbid php HTML


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File acceptbid.php HTMLgenerated code

M SQL () f ti


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MySQL now() function

Returns the current date and time as avalue in 'YYYY-MM-DD HH:MM:SS' orYYYYMMDDHHMMSS.uuuuuu format

depending on whether the function is used ina string or numeric context

The value is expressed in the current time

zone.

Fil tbid h


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File acceptbidprocess.php

R lti d


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Resulting records


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Outline Topic #10 Listing Bids

For Each Bid Item

Li ti bid f h bid it


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Listing bids for each bid item

MySQL date_format() function

Relating information from two or moretables

SQL order by clause

M SQL d t f t() f ti


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MySQL date_format() function

Formats a string based on a specifiedformat

The following are some of the specifies of

the format string: %D: Day of month with English suffix

%d: Numeric day of month (0131)

%M: Month name (JanuaryDecember) %m: Month numeric (0112)

%Y: Year (4 digits)

%y: Year (2 digits)

M SQL d t f t() l


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MySQL date_format() sample

building an online bidding application using php

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