1. 2010/11 : [1]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) PHP with MySQL

2. 2010/11 : [2]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) PHP with MySQL Combining PHP with MySQL is a powerful combination to build applications. MySQL provides a fast structured data store. PHP provides the user interface to this data.

3. 2010/11 : [3]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) mysqli PHP extension PHP communicates with MySQL database using the built-in mysqli extension. http://php.net/manual/en/ref.mysqli.php

4. 2010/11 : [4]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Connect Before using MySQL, a PHP script needs to connect to the database. For this, we use the function mysqli_connect(). Once executed, we check the connection happened OK.

5. 2010/11 : [5]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Connect Example $link = mysqli_connect( ‘mysqlsrv.dcs.bbk.ac.uk’, ‘my_username’, ‘my_password’, ‘my_db_name’ ); /* check connection */ if (mysqli_connect_errno()) { exit(mysqli_connect_error()); }

6. 2010/11 : [6]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Write Queries Write queries like INSERT, UPDATE, DELETE and so on do not return any data. Such queries can be executed using the function mysqli_query. This function returns TRUE on success, and FALSE on failure. Note the query doesn’t need to be terminated with a semi-colon.

7. 2010/11 : [7]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Write Query Example /* add student */ $sql = “INSERT INTO students VALUES (‘Jane’,26,’female’)”; $ok = mysqli_query($link,$sql); if (!$ok) { /* check query ok */ exit(mysqli_error($link)); } NameAgeSex Jane26female Table students

8. 2010/11 : [8]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Read Query Read queries (like SELECT ) need to return data to PHP. The queries are also executed with the function mysqli_query, but this time it returns a result set. $sql = ‘SELECT * FROM students’; $result = mysqli_query($link,$sql);

9. 2010/11 : [9]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Data Retrieval Rows are retrieved one at a time using a number of functions: mysqli_fetch_assoc($result) returns a row as an associative array with the column names as keys. mysqli_fetch_array($result) returns a row as an array with both a numerical and an associative index

10. 2010/11 : [10]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Read Query Example /* get all students */ $sql = “SELECT name,age FROM students”; $result = mysqli_query($link,$sql); /* check query */ if ($result===false) { exit(mysqli_error($link)); } /* fetch associative array */ while ($row = mysqli_fetch_assoc($result)) { echo row[‘name’].’, ’.$row[‘age’].’ yrs old’; } /* free result set */ mysqli_free_result($result); NameAgeSex ……… Table students

11. 2010/11 : [11]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Read Queries Note how the mysqli_free_result($result) function was used to close the result set once the read has completed. Many other MySQL related functions exist, and can be found in the PHP manual: http://php.net/manual/en/ref.mysqli.php

12. 2010/11 : [12]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Escaping Strings Certain characters need to be escaped before they can be used safely in MySql queries. Eg: ‘Student’s marks’ becomes ‘Student\’s marks’ PHP provides functions that do this for us. mysqli_real_escape_string($link, $string) We should pass every variable we want to use in our MySql query to this function.

13. 2010/11 : [13]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Escaping Strings /* Grab a value from $_POST */ $student = $_POST[‘student’]; /* Make the data safe for use in a query. $link must be an existing connection! */ $clean_student = mysqli_real_escape_string( $link, $student); /* (safely) get student */ $sql = “SELECT name,age FROM students WHERE name = ‘”.$clean_student.“’”; $result = mysqli_query($link,$sql);

14. 2010/11 : [14]PHP with MySQLBuilding Web Applications using MySQL and PHP (W1) Exercise Hands On Exercise PHP with MySQL