输出问题与pdo :: fetchall

Question

source code:

<?php
$dsn = 'mysql:dbname=oop;host=localhost;';
$user = 'admin';
$password = 'password';
try {
$pdo = new PDO($dsn, $user, $password);
} catch (PDOException $e)
{
echo 'Connection failed: ' . $e->getMessage();
}
$stmt = $pdo->prepare("select * from be_users");
$stmt->execute();
echo "<pre>";
print_r($stmt->fetchAll());
echo "</pre>";
?>

result:

Array
(
    [0] => Array
        (
            [username] => tom
            [0] => tom
            [email] => [e-mail]
            [1] => [e-mail]
        )

    [1] => Array
        (
            [username] => tom3
            [0] => tom3
            [email] => [e-mail]
            [1] => [e-mail]
        )
     ...

Question:

Why the result is not like this:

Array
(
    [0] => Array
        (
            [username] => tom
            [email] => [e-mail]
        )

    [1] => Array
        (
            [username] => tom3
            [email] => [e-mail]
              )

Answer 1

You are using the default fetch style, which is PDO::FETCH_BOTH, meaning that you will get an array indexed both numerical and associative. Use PDO::FETCH_ASSOC instead:

print_r($stmt->fetchAll(PDO::FETCH_ASSOC));

You'll find more information about fetch styles in the manual page of PDOStatement::fetchAll()

Note that you can specify the fetch mode per statement or globally per PDO instance:

$pdo->setAttribute(PDO::ATTR_DEFAULT_FETCH_MODE, PDO::FETCH_ASSOC);