CODEWITHSUNDEEP
phpsqlpdo
qpA
qpA

Reputation: 95

proofing if user exist in database or not - using pdo

I want to check if a user (email) ist already in the database or not.

    $email_pruefen = ($_GET['email']);

    //SQL Statement ob email bereits existiert
    try {
            $stmt = $pdo->prepare("SELECT rechnungsmail FROM kundendaten WHERE rechnungsmail = :checkmail");
            $stmt->execute([':checkmail' => $email_pruefen]);
            $fetchergebnis = $stmt->fetchAll(); //entnimmt alles aus dem Statement (Value, True/False, ..)

            if($fetchergebnis[0] > 0){
                $ergebnis = "Ja"; //Eintrag ist vorhanden
            } else {
                $ergebnis = "Nein"; //Eintrag ist nicht vorhanden
            }

            $pdo = null; //Verbindung schließen

    } catch (PDOException $e) {
        $meldung_checkemail = "Überprüfung der E-Mail Adresse war ohne Erfolg. Bitte wenden Sie sich an die IT.";
        echo "<script type='text/javascript'>alert('$meldung_checkemail');</script>";

        die();
    }


if($ergebnis == "Nein"){ //Wenn Email nicht existiert, führe folgendes aus
 ... create user ...
}else{
 ... dont create user ...
}

If there is no existing entry, the user can create it.

but my code dont work :I any ideas?

Upvotes: 0

Views: 69

Answers (2)

Carl Binalla
Carl Binalla

Reputation: 5401

I tested if($fetchergebnis[0] > 0) using var_dump(), and it seems that this returns a Undefined offset:0 plus bool(false) when the statement fetched nothing (tested it because I never tried using it before)

One way is to use rowCount() before fetching to check if any row has been returned by the SELECT statement, something like this:

$stmt = $pdo->prepare("SELECT rechnungsmail FROM kundendaten WHERE rechnungsmail = :checkmail");
$stmt->execute([':checkmail' => $email_pruefen]);

$ergebnis = ($stmt->rowCount() > 0) ? 'Ja' : 'Nein';

OR

Since you are just checking if something exist and not needing to use any data fetched from it, you can also use COUNT(*):

$stmt = $pdo->prepare("SELECT COUNT(*) FROM kundendaten WHERE rechnungsmail = :checkmail");
$stmt->execute([':checkmail' => $email_pruefen]);
$count = $stmt->fetchColumn();
$ergebnis = ($count > 0) ? 'Ja' : 'Nein';

Upvotes: 1

Your Common Sense
Your Common Sense

Reputation: 157880

Your problem is that your are comparing a string (email) with a number (0). In this case a string will be converted to a number and become 0. 0 is not bigger than 0, so your condition returns false

Use just $fetchergebnis in your comparison and it would work. PHP is a loosely typed language, you can use a variable of almost any type in a conditional operator and any "non-empty" value wold work as true. A non-empty array as well.

Better yet, instead of fetchAll() which is unsuitable for this case, use a more appropriate fetchColumn() (but nevertheless check the direct result, the actual variable you get from fetch)

A canonical solution for your task: How to check if email exists in the database?

Upvotes: 4

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