Get the results from database by ID

[MuphN]

Hello. I need some help making a script (udnerstanding it).

So I need to get for exemple "Thing" from detabase  by salecting id witch user is logged in now.

 

This is to check if user is logged in.

function login_check($mysqli) {
    // Check if all session variables are set 
    if (isset($_SESSION['user_id'], 
                        $_SESSION['username'], 
                        $_SESSION['login_string'])) {
 
        $user_id = $_SESSION['user_id'];
        $login_string = $_SESSION['login_string'];
        $username = $_SESSION['username'];
 
        // Get the user-agent string of the user.
        $user_browser = $_SERVER['HTTP_USER_AGENT'];
 
        if ($stmt = $mysqli->prepare("SELECT password 
                                      FROM members 
                                      WHERE id = ? LIMIT 1")) {
            // Bind "$user_id" to parameter. 
            $stmt->bind_param('i', $user_id);
            $stmt->execute();   // Execute the prepared query.
            $stmt->store_result();
 
            if ($stmt->num_rows == 1) {
                // If the user exists get variables from result.
                $stmt->bind_result($password);
                $stmt->fetch();
                $login_check = hash('sha512', $password . $user_browser);
 
                if ($login_check == $login_string) {
                    // Logged In!!!! 
                    return true;
                } else {
                    // Not logged in 
                    return false;
                }
            } else {
                // Not logged in 
                return false;
            }
        } else {
            // Not logged in 
            return false;
        }
    } else {
        // Not logged in 
        return false;
    }
}

And I need to get the the thing from detabase table named Members. and name it a $.

I know how to get it, but I dont know how to get from logged id now. (ID). For exemple user loggs in and it should show Hes satus from thing.

[Ch0cu3r]

There already is a query that is using the users_id to get the password. You can change this query so it gets both the password and Thing

 

To do this change   $mysqli->prepare("SELECT password   to   $mysqli->prepare("SELECT password, Thing

 

Not to assign Thing to a variable change  $stmt->bind_result($password);   to   $stmt->bind_result($password, $thing);

 

$thing  now holds the value in the Thing column for current logged in user.

[MuphN]

So after this I could just do echo $Thing; right and it will print the Thing from the detabase witch is from the right User ID - Logged in now?

[mac_gyver]

a function who's name is login_check() should only check if the current user is logged in. the purpose of that function is not to retrieve any arbitrary user information. the user information it happens to retrieve are for the purpose of authenticating the user.

 

after your code calls login_check() and it returns true, you know that the current user is logged in and you can use his $_SESSION['user_id'] to then query for any information you have stored for that user.

[Ch0cu3r]

MuphN Yes, however with your code as-is (with the changes I suggested) $thing will only be accessible from within the login_check() function. You wont be able to use this variable outside of this function. This is due to variable scope. 

Edited January 25, 2014 by Ch0cu3r

[MuphN]

so should I create new function?  and use it on other?

function getThing($mysqli) {

    if ($stmt = $mysqli->prepare("SELECT Thing FROM members WHERE id = ? LIMIT 1")) {

 

            $stmt->bind_param('i', $Thingy);

            $stmt->execute();   // Execute the prepared query.

            $stmt->store_result();

            if ($stmt->num_rows == 1) {

                // If the user exists get variables from result.

                $stmt->bind_result( $Thing);

                $stmt->fetch();

}

 

hmmm I still dont understand this quet well. I think I made up a nonsense for this function.

But if it would be ok then I would echo getThing; ??

[Ch0cu3r]

so should I create new function?

 

Yes. Do it in another function. 

 

Your code for the function is almost there, a few changes are required. First you need to get the user_id from $_SESSION['user_id'] not $Thingy

$stmt->bind_param('i', $_SESSION['user_id']); // pass users id to query

Now change $stmt->fetch(); to

                $stmt->fetch();
                return $Thing; # return users Thing value
          } # close if for $stmt->num_rows
    } # close if for $stmt = $mysqli->prepare

    return false; # return false

When you call getThing() you'd do

$usersThing = getThing($mysqli); // get the users thing

Edited January 25, 2014 by Ch0cu3r

[MuphN]

function getThing($mysqli) {

    if ($stmt = $mysqli->prepare("SELECT Thing FROM members WHERE id = ? LIMIT 1")) {

            $user_id = $_SESSION['user_id'];

            $stmt->bind_param('i', $user_id);

            $stmt->execute();

            $stmt->store_result();

            if ($stmt->num_rows == 1) {

                $stmt->bind_result( $Thing);

                $stmt->fetch();

                return $Thing;

        }
    }
  return false;

}

 

$usersThing = getThing($mysqli); // get the users thing

 

Then I should use 

echo $usersThing; as I understood? 

Edited January 25, 2014 by MuphN

[Ch0cu3r]

Yes.

[MuphN]

what is return false; for in that function? i mean, If the function called it should show, there is no else.

OR Should I make
$usersThing = getThing($mysqli);

if ($usersThing === True) {

   return true;

}else{

  return false;

} 

 

If that works. hmmm

[Ch0cu3r]

The function will return false when the prepared statement fails or the query did not return a result. It will only return the value of $thing when a result is returned from the query.

 

You can add an else if you want, but it is optional in this case. Another way to code the function

     if ($stmt = $mysqli->prepare("SELECT Thing FROM members WHERE id = ? LIMIT 1")) {
            $user_id = $_SESSION['user_id'];
            $stmt->bind_param('i', $user_id);
            $stmt->execute();
            $stmt->store_result();
            if ($stmt->num_rows == 1) {
                $stmt->bind_result( $Thing);
                $stmt->fetch();
                return $Thing;
        } else {
            return false; // query did not return 1 row
        } 
    } else {
        return false; // prepared statement failed
    }

Outcome will still be the same

Edited January 25, 2014 by Ch0cu3r

[MuphN]

Okey I understand it now. Thanks again for saving my script.

Gratefull!! ))

and thx mac_graver for taking your time to help me aswell!

 

Awesome. 

[mac_gyver]

your current function is tied to one specific id, the currently logged in user's id. to make a general purpose function that could retrieve data for any user's id, for example in a game, a profile page, a pm system, the id should be a call time parameter into the function.

 

then to use the general purpose function specifically for the currently logged in user you would call it -

$thing = getThing($mysqli,$_SESSION['user_id']);