从数据库值填充数组的最有效方法？

Question

如果我想获取某个品牌的product_ids 列表。我会这样做：

$id_list = array();
$qry = 'SELECT product_id FROM products WHERE product_brand = :brand';
$STH = $this->pdo->prepare($qry);
$STH->execute(array("brand" => $brand));
$STH->setFetchMode(PDO::FETCH_ASSOC);
while($row = $STH->fetch())
{
    $id_list[] = $row['product_id'];
}

有没有更快更有效的方法？似乎如果我只选择一列，应该有更好的方法来选择/插入到数组中。

Answer 1

$STH->setFetchMode(PDO::FETCH_COLUMN,0);
$id_list = $STH->fetchAll();

真的更快吗？本地基准：

$ cat 1.php 
<?php
$d = new PDO('mysql:localhost');
$qry = 'SELECT SQL_NO_CACHE bar FROM test.foo'; //for completeness sake: foo has 400 rows
$stmt = $d->query($qry);
$stmt->setFetchMode(PDO::FETCH_COLUMN,0);
$check = $stmt->fetchAll();
?>
$ cat 2.php 
<?php
$d = new PDO('mysql:localhost');
$qry = 'SELECT SQL_NO_CACHE bar FROM test.foo'; //for completeness sake: foo has 400 rows
$stmt = $d->query($qry);
$check = array();
$stmt->setFetchMode(PDO::FETCH_ASSOC);
while($row = $stmt->fetch()){
        $check[] = $row['bar'];
}
?>
$ time (for i in {1..100}; do php 1.php; done;)

real    0m4.507s
user    0m2.392s
sys     0m1.288s
$ time (for i in {1..100}; do php 2.php; done;)

real    0m6.830s
user    0m3.352s
sys     0m2.328s

..所以，至少这个脚本差异在我的服务器上更快......