Integrating PHP functions with a database - php

Question

I just submitted my work and my course leader has asked me to use PHP functions to query my database. How can I do this? Is it possible to add just "function getRooms" before my queries, and return the desired result. I need thorough briefing on functions with MySQL.
For example:
How will I add a function to this code:
<?php
// By Kelvin
include ("player.php");
$result = mysql_query("SELECT * FROM phplogin WHERE username = '$username'");
$row = mysql_fetch_assoc($result);
$medipack = $row['medipack'];
if ($_POST['object'] == "Use Medipack") {
if ($medipack != 0) {
mysql_query("UPDATE phplogin SET score = score + 50, health = health + 50, medipack = medipack - 1
WHERE username = '$username'");
echo ("<P>Medipack Used!</P>");
$RoomNumber =5;
}
else {
echo ("<P>You're all out of medipacks!</P>");
}
}
?>

Answer 1

If he's looking for a level of abstraction between the rest of your code and the code accessing the database, wrapping the database logic in functions should be on the right path:
function getRooms($link){
$sql = "SELECT * FROM rooms";
$data = array();
if($set = mysql_query($sql)){
while($row = mysql_fetch_assoc($set)){
$data[] = $row;
}
}
return empty($data)
? null
: $data;
}
$db_connection = mysql_connect('host', 'user', 'pass');
mysql_select_db('name', $db_connection);
$rooms = getRooms($db_connection);
Wrapping these functions into a class, and accessing them by methods is another step, as the instantiated object can manage its own connection, etc., but that may be a step further than necessary. Other functions (based on what I can guess) might be:
function getRoomById($link, $id){ }
function getRoomsByName($link, Array $names){ }

Answer 2

I would imagine your course leader is referring to the PHP's native MySQL functions - http://php.net/manual/en/book.mysql.php

Answer 3

You can wrap your queries inside PHP functions. For example, like this:
function &getRooms(){
$query="SELECT id,name FROM rooms";
$result=mysql_query($query);
$ar_out=array();
while ($row = mysql_fetch_assoc($result)) {
$ar_out[]=$row;
}
return $ar_out;
}
This said, you really should find a tutorial or a book on how to use MySQL and PHP together. There are many things to know about code organization and performance.