I have a MySQL database that holds a list of classes in columns, and each class has a "level" which is the value of the row, which changes for each person. So, math, for example, has 0, 1, 2, and 3 as possible values, 0 being not selected as a class, and 1, 2, and 3 being high, medium, and low, respectively.
I have a MySQL query which pulls just the classes from a user's database row.
$result = mysql_query("SELECT math, physics, biology, chemistry, english, spanish, history, economics, art, theoryofknowledge, extendedessay FROM users WHERE username = '". $login_session ."'") or die(mysql_error());
while($row = mysql_fetch_array( $result )) {
echo "Math:". $row['math'] ."<br />";
echo "Physics:". $row['physics'] ."<br />";
echo "Biology:". $row['biology'] ."<br />";
echo "Chemistry:". $row['chemistry'] ."<br />";
echo "English:". $row['english'] ."<br />";
echo "Spanish:". $row['spanish'] ."<br />";
echo "History:". $row['history'] ."<br />";
echo "Economics:". $row['economics'] ."<br />";
echo "Art:". $row['art'] ."<br />";
echo "Theory of Knowledge:". $row['theoryofknowledge'] ."<br />";
echo "Extended Essay:". $row['extendedessay'];
}
Here is the output for a user:
Math:1
Physics:1
Biology:0
Chemistry:2
English:2
Spanish:3
History:0
Economics:1
Art:0
Theory of Knowledge:1
Extended Essay:1
How could I determine which level a user has, without doing an if statement for every single time the class is called? I need to call the classes in multiple places on the site, and I'd like an easy way to check which classes, and level, the user has.
Thanks!
I think the best approach would be to build a PHP class that loads the user in and inside it have a function that can accept a class (Biology, Math etc) and return the level of the user. If you wanted to, you could write something simple that performs a check of the level required and returns a true or false depending on if the user is a high enough level.
I even slapped together some super basic structure you might want to extend upon:
<?php
class myUser
// You are making an object here that stores information about your user.
// This will mean you only need to query that data once from the DB, then
// you can use it anywhere on the page without needing to do more queries.
{
public $math;
public $biology;
// I am making public variables here based on your columns
// You cuold just as easily make an array for example to store them in.
public function __construct($userID)
// Making a construct class - meaning you will be able to write a snippet
// like this: $currentUser = new myUser(6);
// and the user information will be loaded nicely for you
{
$query="select math, biology from users where ID=$userID";
// database stuff ....
// this is where you would write your actual code to get the info
// from the database and populate it properly, not like I did
// below for this example
$this->math=4;
$this->biology=2;
}
public function checkUserLevel($myTopic, $reqLevel)
// Making use of a few things here that I should ntoe:
// This is a function you can call from the main code below
// like this: $currentUser->checkUserLevel('math',3)
// it will return either true or false.
// I have used variable variables here for the $myTopic to
// make it easier. You normally access an element differently
// normally it is like: echo $this->math; // output 4
// Also I am using a ternary operator to return the data,
// which is just a shortcut.
{
return ($this->$myTopic>=$reqLevel)? true : false;
}
public function returnUserLevel($myTopic)
{
return $this->$myTopic;
}
}
$currentUser = new myUser(6);
// This is creating a new user object based on the class we made above.
// Further Explanation:
// We have a class called myUser, but a class is just a schematic.
// The $currenUser bit defines a new variable in our code.
// the "= new myUser" bit says that we want to use the schematic above for this variable
// the "myUser(6)" basically gives the constructor function an ID to get from
// the database for the user. Because we defined a constructor class that expects
// an ID, we need to supply it one, else we will get an error.
// So $currentUser = new myUser(6)
// really means "Make me a new variable called $currentUser and make it of the myUser
// class type, and when making it, fetch me the details of student ID 6 and populate it
// with their data.
if($currentUser->checkUserLevel('math',3))
// Now I am using one of the functions called checkUserLevel, supplying it
// with the two arguments it needs and depending on it it returns true or false
// doing one action or another.
{
echo "The user is at least level 3.\n";
}
else
{
echo "The user is lower than level 3.\n";
}
if($currentUser->checkUserLevel('biology',12))
// same check, differnt inputs
{
echo "The user is at least level 3.\n";
}
else
{
echo "The user is lower than level 3.\n";
}
// You can output like this for example:
echo "The users math is at: ".$currentUser->math;
// and I added a little function that will simply return the level for you of the subject you enter.
echo "The user is at math level ".$currentUser->returnUserLevel('math');
// lastly you can do something like this:
$allSubjects=array('math','physics','biology');
for($i=0;$i<count($allSubjects);$i++)
{
echo "The users ".$allSubjects[$i]." level is at ".$currentUser->returnUserLevel($allSubjects[$i])."<br><br>";
}
?>
The output of code is:
The user is at least level 3.
The user is lower than level 3.
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