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Use of PHP for DB Connection

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Client:UI

Middle Get all books with keyword “web programming”

DBQuery

Format the output, i.e., data returned from the DBPHP

HTML, JavaScript, CSS,XML

SQL

Access/MySQL

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Middle and Information TierPHP: built in library functions for interfacing with the mySQL database management system

$id = mysqli_connect(string hostname, string username, string password, string db)

Connection to the MySQL serverReturn false if fails

$result = $id->query(string query)Execute a SQL query: return a result handle that will be used to fetch the result

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Middle and Information TierPHP: built in function for mySQL

$result->data_seek(0);Go to the first row of the result

$row=$result->fetch_assoc()Fetch the row of the results Combine with a while loop to read all rows

$id->close()Close the connection

StepsCreate DB “pharmacy”

dbPharmacy.txtlocalhost/phpmyadmin

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Define a SQL string

Execution

Data processing

DB connection

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ExerciseModify previous examples to show the following info:

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Database Modification: InsertSyntax:

INSERT INTO table_name VALUES (value1, value2, ….)

Step:DB connectionDefine a string containing the SQL commandExecute the sql statement

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Database Modification: ModifySyntax:

UPDATE table_name SET column_name_i = new_value where column_name_j=some_value

Step:DB connectionDefine a string containing the SQL commandExecute the sql statement

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AJAX and DB

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AJAX and DatabaseDisplay info in one page

Display info whenever the info is received

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A Possible ApproachUsing get method

If there is a salesperson’s name in the URL, then display the required informationOtherwise, display the form only

Require HTML or PHP file?Two parts:

a form to be displayedA db query to display the required info

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<form method="GET" action=“query2.php"><p> Select a salesperson to display the info:

<select name="select"><option value="Abel" selected="selected"> Abel </option><option value="Baker"> Baker </option><option value="Jones"> Jones </option><option value="Kobad"> Kobad </option><option value="Murphy"> Murphy </option><option value="Zenith"> Zenith </option>

</select> </p><p> <input type="submit" value="Query" /> </p>

</form>

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<?phpif (isset($_GET["select"]) and $_GET["select"] !=NULL) {

$q = $_GET["select"]; $conn = mysqli_connect("localhost", "root", "","pharmacy");if ($conn->connect_error) {

echo "Unable to connect to database"; exit; }print("<h1> Sales person: " . $q . "</h1>");$query1 = "select salary from salesperson where

SalesName= '" . $q . "'";$result1 = $conn->query($query1);if (!$result1) die("No information");$result1->data_seek(0);while ($row=$result1->fetch_assoc()) {

print("<h2> Salary: " . $row["salary"] . "</h2>");} …

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SynchronousAsynchronousAsynchronous requests

Browser Server

Request the php file

Display the form only

A get request

Display the form + order info

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AJAX Approach2 files

Html fileA formA JavaScript function

Make asynchronous connectionCall to the php file, display the information when it is ready

Php fileQuery the db to get the desired info

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<script type="text/javascript">var xmlHttp;function showInfo(str) {

try{ xmlHttp = new XMLHttpRequest();} catch (e){

try{xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");

} catch (e) {try{

xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");} catch (e){

alert(“Error!"); return ;}

}}

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var url = "phpSales.php?q=" + str;

xmlHttp.onreadystatechange=function() {if (xmlHttp.readyState == 4) {

disInfo.innerHTML = xmlHttp.responseText;}

}xmlHttp.open("GET", url, true);xmlHttp.send(null);

}</script>

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<form><p> Select a salesperson to display the info:

<select name="select" onchange="showInfo(this.value)"><option value="Abel" selected="selected"> Abel </option><option value="Baker"> Baker </option><option value="Jones"> Jones </option><option value="Kobad"> Kobad </option><option value="Murphy"> Murphy </option><option value="Zenith"> Zenith </option>

</select> </p></form><div id="disInfo"> </div>

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display.php$q = $_GET["select"]; $conn = mysqli_connect("localhost", "root", "","pharmacy");if ($conn->connect_error) {

echo "Unable to connect to database"; exit; }print("<h1> Sales person: " . $q . "</h1>");$query1 = "select salary from salesperson where

SalesName= '" . $q . "'";$result1 = $conn->query($query1);if (!$result1) die("No information");$result1->data_seek(0);while ($row=$result1->fetch_assoc()) {

print("<h2> Salary: " . $row["salary"] . "</h2>");} …

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POST

var url = ”display.php";var queryvalue = encodeURIComponent(str);var parameters = "q="+queryvalue;xmlHttp.open("POST", url, true);xmlHttp.setRequestHeader("Content-type",

"application/x-www-form-urlencoded");xmlHttp.send(parameters);

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Application designDesign application in tiersEach tier can be run a separate machine, allowing for improved processing performancePromote scalabilityEase long term maintenance requirements for your code

Client tier Middle tier Information tier

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Application designPHP:

Server side scripting languageSQL:

Language used to query the relational databaseWHERE, ORDER BY, COUNT(*)

Processing in PHP or SQL?Sorting, pattern matching in records

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Application designSQL:

Language specifically designed to query and retrieve data from your tables!!

Filter out unnecessary data using SQL, leaving a relevant data set for PHP to work with

Selecting statement, WHERE conditionORDER BY: sorting

FASTER CODE, NETWORK LOAD

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ComponentsSetting up a siteDesign the web documents

Client side techniques: CSS, JavaScript, DHTML

Server side techniquesScripting languages, how to access database

Administrating a web site: IMPORTANTDifficult to keep all documents/information up to date easily

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InformationMaintenance of a content-driven site can be a real painSolution: database-driven site designComplete separation between the site design and the content you want to presentDon’t write an HTML file for every page of your siteWrite a page for each kind of information you want to present

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IdeaDatabase:

content of the siteDynamically pulled from the database to create web pages

Template HTML page:

For each kind (type) of information

browserWeb server

PHP fileMySQ

L

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ModelOn the visitor’s end:

Expects to view a standard HTML web page

On the other endHave a database that only understands how to respond to SQL queries

PHP scripting languagego-between that speaks both languages