Use of PHP for DB Connection. Middle and Information Tier

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the mysql database management system $id = mysqli_connect(string hostname, string username, string password, string db) Connection to the MySQL

1 Client: UI HTML, JavaScript, CSS, XML Use of PHP for DB Connection Middle Get all books with keyword web programming PHP Format the output, i.e., data returned from the DB SQL DB Query Access/MySQL 1 2 Middle and Information Tier PHP: 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 server Return false if fails $result = $id->query(string query) Execute a SQL query: return a result handle that will be used to fetch the result 3 4

2 Steps Middle and Information Tier PHP: 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 Create DB pharmacy dbpharmacy.txt localhost/phpmyadmin 5

3 DB connection Define a SQL string Execution Data processing 11 12

4 Exercise Modify previous examples to show the following info: Database Modification: Insert Syntax: INSERT INTO table_name VALUES (value1, value2,.) Step: DB connection Define a string containing the SQL command Execute the sql statement Database Modification: Modify Syntax: UPDATE table_name SET column_name_i = new_value where column_name_j=some_value Step: DB connection Define a string containing the SQL command Execute the sql statement AJAX and DB 15 16

AJAX and Database Display info in one page Display info whenever the info is received A Possible Approach Using get method If

PHP file? Two parts: a form to be displayed A db query to display the required info 17 18 <form method="get" action= query2.

</option> <option value="baker"> Baker </option> <option value="jones"> Jones </option> <option value="kobad"> Kobad </option>

5 AJAX and Database Display info in one page Display info whenever the info is received A Possible Approach Using get method If there is a salesperson s name in the URL, then display the required information Otherwise, display the form only Require HTML or PHP file? Two parts: a form to be displayed A db query to display the required info <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> 20

6 <?php if (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>"); 21 Browser Request the php file Display the form only A get request Display the form + order info Asynchronous requests Server Asynchronous Synchronous 22 AJAX Approach 2 files Html file A form A JavaScript function Make asynchronous connection Call to the php file, display the information when it is ready Php file Query the db to get the desired info <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 ; 23 24

var url = "phpsales.php?q=" + str; xmlhttp.onreadystatechange=function() { if (xmlhttp.readystate == 4) { disinfo.innerhtml = xmlhttp.responsetext; xmlhttp.open("get", url, true); xmlhttp.

7 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> <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> 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>"); 27

8 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); Application design Design application in tiers Each tier can be run a separate machine, allowing for improved processing performance Promote scalability Ease long term maintenance requirements for your code Client tier Middle tier Information tier Application design PHP: Server side scripting language SQL: Language used to query the relational database WHERE, ORDER BY, COUNT(*) Processing in PHP or SQL? Sorting, pattern matching in records Application design SQL: 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 condition ORDER BY: sorting FASTER CODE, NETWORK LOAD 31 32

Setting up a site Components Design the web documents Client side techniques: CSS, JavaScript, DHTML Server side techniques Scripting languages, how to access database Administrating a web site:

9 Setting up a site Components Design the web documents Client side techniques: CSS, JavaScript, DHTML Server side techniques Scripting languages, how to access database Administrating a web site: IMPORTANT Difficult to keep all documents/information up to date easily Information Maintenance of a content-driven site can be a real pain Solution: database-driven site design Complete separation between the site design and the content you want to present Don t write an HTML file for every page of your site Write a page for each kind of information you want to present Idea Model Database: content of the site Dynamically pulled from the database to create web pages Template HTML page: For each kind (type) of information browser Web server PHP file MySQ L On the visitor s end: Expects to view a standard HTML web page On the other end Have a database that only understands how to respond to SQL queries PHP scripting language go-between that speaks both languages 35 36

Use of PHP for DB Connection. Middle and Information Tier. Middle and Information Tier

Use of PHP for DB Connection. Middle and Information Tier. Middle and Information Tier Use of PHP for DB Connection 1 2 Middle and Information Tier PHP: built in library functions for interfacing with the mysql database management system $id = mysqli_connect(string hostname, string username,