MySQL database data manipulation

, PHP, , , (Biology, Math ..) . , - , true false , .

- , , , :

<?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 user is at least level 3.

The user is lower than level 3.