Jquery ui js回归

i use jquery ui js.

When i return result i am doing this:

$stmt = $dbh->prepare('SELECT id,value FROM `table` WHERE `column` LIKE :keyword');
$keyword = "%".$data."%";
$stmt->bindParam(':keyword', $keyword, PDO::PARAM_STR);
$stmt->execute();   
while ($user = $stmt->fetch(PDO::FETCH_ASSOC)) {
    $user['value']=htmlentities(stripslashes($user['column']));
    $user['id']=(int)$user['id'];
    $user_set[] = $user;
}

And the returned array:

[{"id":1,"column":"user","value":"user"}]

I just set $user[id] and $user['value'], but there are three things returned , why?

Greetings!

while ($user = $stmt->fetch(PDO::FETCH_ASSOC)) {
       ^^^^^