How to insert unique email into mysql table [duplicate] - php

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How to prevent duplicate usernames when people register?
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Closed 12 months ago.
I want to take email addresses from users to add them to a mailing list. However, I want to prevent duplicate entries, so I am using the INSERT IGNORE approach. I am using the PHP script below, but constantly receive this error:
Fatal error: Uncaught Error: Call to a member function bind_param() on bool
I've reviewed a LOT of SO articles on this error but still can't get it to work. I have confirmed that the $email and $id variables do have values. I suspect the error must have something to do with the use of IGNORE, but I honestly don't know.
Here's my code:
$email = filter_input(INPUT_POST, 'email',FILTER_SANITIZE_EMAIL);
$id = filter_input(INPUT_POST, 'id',FILTER_VALIDATE_INT) ?: NULL;
$sqlQuery = 'INSERT IGRNORE INTO email(email, id) VALUES(:email,:id);';
$stmt = $dbc->prepare($sqlQuery);
$stmt->bind_param(':email',$email);
$stmt->bind_param(':id',$id);
$stmt->execute();
mysqli_close($dbc);
I've tried including only one variable for the insert but I get the error against both bind_param lines. I also got the error when I had this structured to have both variables in a single bind_param entry.
I'm open to other ways of avoiding duplicate emails in the database, so long as they can be done with a single PHP file.

Answer 1

You are mixing PDO and mysqli syntax. You need to pick one.
PDO
Open the connection, execute the statement without IGNORE, and then catch the exception to see why it failed. The code 1062 means that MySQL tried to insert a duplicate value.
$pdo = new PDO("mysql:host=localhost;dbname=test;charset=utf8mb4", 'user', 'pass', [
\PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
\PDO::ATTR_EMULATE_PREPARES => false
]);
try {
$stmt = $pdo->prepare('INSERT INTO email(email, id) VALUES(:email,:id)');
$stmt->execute([
'email' => $email,
'id' => $id
]);
} catch (PDOException $e) {
if ($e->errorInfo[1] === 1062) {
// duplicate
} else {
// If not 1062 then rethrow
throw $e;
}
}
mysqli
Using mysqli it's a little bit more work, but the same logic. With mysqli you can't use named placeholders and you can't bind-in-execute. The bind_param() function is very peculiar so pay special attention to the syntax.
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$mysqli = new mysqli('localhost', 'user', 'pass', 'test');
$mysqli->set_charset('utf8mb4'); // always set the charset
try {
$stmt = $mysqli->prepare('INSERT INTO email(email, id) VALUES(?, ?)');
$stmt->bind_param('ss', $email, $id);
$stmt->execute();
} catch (mysqli_sql_exception $e) {
if ($e->getCode() === 1062) {
// duplicate
} else {
// If not 1062 then rethrow
throw $e;
}
}