Networks and Web for Health Informatics (HINF 6220) Tutorial 13 : PHP 29 Oct 2015

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1 Networks and Web for Health Informatics (HINF 6220) Tutorial 13 : PHP 29 Oct 2015

2 PHP Arrays o Arrays are single variables that store multiple values at the same time! o Consider having a list of values that you want to loop through them: $person1 = Jerry ; $person2 = Marta ; $person100 = Anne ; echo $person1; o Using an Array you can store all values in echo $person100; one variable and access them by an index number: $person = array ( Jerry, Marta,, Anne ) # loop through the array and echo each name

3 PHP Arrays o How to access an array item? Use the index of item in the array, according to the order of storage, starting by 0 : $person = array ( Jerry, Marta,, Anne ) echo $person [ 0 ]; $person [ 1 ] = John ; o You can loop through an array using a for loop and the size of the array (count function): $person = array ( Jerry, Marta,, Anne ); $arraylength = count ($person); for ($i = 0; $i < $arraylength; $i++) { echo $person [ $i ]; echo "<br>";

4 PHP Conditional Statements if o You can use conditional statements to perform different actions in different situations. o One of PHP conditional statements is if else. This statement executes your code if a certain condition holds true: if (condition 1 ) { execute some code here else if (condition 2 ) { execute this code if second condition is true else { if none of the above conditions are true, execute this

5 PHP Conditional Statements Example $num = 17; if ($num < 10) { echo num less than 10 ; else if ($num >=10 && $num =< 20) { echo num within ; else { echo num greater than 20 ; $num = 17; if ($num < 10) { echo num less than 10 ; if ($num >=10 && $num =< 20) { echo num within ; if ($num > 20) { echo num greater than 20 ;

6 PHP and MySQL o You can use PHP to easily interact with a MySql database programmatically. To do this, follow four simple steps: 1. Get your connection properties ready. 2. Open a connection from your PHP code to the MySql server. 3. Execute your MySql query. 4. Close the connection you have opened from PHP to MySql server.

7 PHP and MySQL o You can use PHP to easily interact with a MySql database programmatically. To do this, follow four simple steps: 1. Get your connection properties ready. Every connection to a database requires a server name, database name, username and password. In our case, we can use PHP variables to prepare our connection properties: $servername = "db.cs.dal.ca"; $username = your user name"; $password = your password"; $dbname = your database name";

8 PHP and MySQL 2. Open a connection from your PHP code to the MySql server. To establish the connection between PHP and MySql, you need to create the connection variable, and send the request to establish it (opening the connection): $conn = new mysqli ( $servername, $username, $password, $dbname ); # Check if connection is stablished successfully. If not, print the error and exit. if ($conn->connect_error) { die("connection failed: ". mysqli_connect_error() );

9 PHP and MySQL 3. Execute your MySql query. An SQL query can be executed using the mysqli_query function, which returns your result set: $sql = "SELECT id, firstname, lastname FROM tbldoctors"; $result = mysqli_query ( $conn, $sql ); # if the number of rows in the result set is greater than 0 if ( mysqli_num_rows($result) > 0) { # output data of each row for ( $i =0; $i < mysqli_num_rows($result); i++ ) { $row = mysql_fetch_assoc($result); # Retrieve the next row on the result set echo "id: ". $row[ id"]. ", Name: ". $row[ firstname"]. $row[ lastname"]."<br>"; else { echo "0 results";

10 PHP and MySQL 4. Open a connection from your PHP code to the MySql server. Don t forget to close your established connection after you are finished (to avoid tiding up your database resources): # step 1, open a connection $conn = new mysqli ( $servername, $username, $password, $dbname ); # step 2 and 3 # close the connection at the end: mysqli_close ( $conn );

11 PHP and MySQL Example $server = "db.cs.dal.ca"; $user = " "; $pass = " "; $db = " "; $conn = new mysqli ( $servername, $username, $password, $dbname ); # open connection if ($conn->connect_error) { die("connection failed: ". $conn->connect_error ); $sql = "SELECT id, firstname, lastname FROM tbldoctors"; # the SQL query $result = $conn->query ($sql ); # execute the SQL query if ($result->num_rows > 0) { # if the results are not empty # output data of each row for ( $i =0; $i < ($result->num_rows; $i++ ) { $row = $result->fetch_assoc(); # retrieve the next row on the result set echo "id: ". $row["id"]. ", Name: ". $row["firstname"]. $row["lastname"]."<br>"; else { echo "0 results"; 4. $conn->close(); # close the connection at the end: