用于更新多行的PDO循环 - PDO loop for updating multiple rows

我有一个检索多行数据的表单，每个项都有一个文本区域，供用户对特定项进行评论。返回的项目数量是可变的，他们不必在任何/所有框中留下评论。

    <textarea name="comment[]" cols="25" rows="2"><?php echo $f2; ?></textarea>
    <input name="tableid[]" type="hidden" value="<?php echo $f1; ?>">

echo语句使用当前存储在数据库中的内容填充文本区域，因为用户可以修改其他人输入的内容。

当它被传递到表单处理页面时，它会返回这个。。

    Submit: Submit
    comment: Test Comment 1,Test Comment 2
    tableid: 590,591

因此它似乎正确地通过了数组。我正在使用此代码更新数据库

$conn = new PDO("mysql:host=xxxx;dbname=xxxxx",$username,$password);
$i = 0;
if(isset($_POST['submit'])) {
    foreach($_POST['comment'] as $comment) {
                        $comment = $_POST['comment'][$i];
            $id = $_POST['tableid'][$i];
            $stmt = $conn->prepare("UPDATE reservations SET comment=:comment WHERE     tableid=:id");
            $stmt->bindValue(':comment', $comment, PDO::PARAM_INT);
            $stmt->bindValue(':id', $id, PDO::PARAM_INT);
            $stmt->execute();
            $i++;
    }
}

然而，这似乎根本没有更新，我哪里出了问题？

非常感谢

很少有东西：

将PDO设置为在出现错误时抛出PDOException。这将使调试更加容易
准备好的语句的意义在于，您可以使用不同的变量多次调用它，也就是说，您只需要准备一次，然后多次调用它。你也从中获得了不错的性能提升

代码：

    $conn = new PDO("mysql:host=xxxx;dbname=xxxxx", $username, $password, [
        PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, //Set PDO to fire PDOExceptions on errors.
        PDO::ATTR_EMULATE_PREPARES => false //Disable emulated prepares. Solves some minor edge cases.
    ]);
//No need for incrementer. The index of the comment should be enough.
    if (isset($_POST['submit'])) {
        //Note the prepare on the outside.
        $stmt = $conn->prepare("UPDATE `reservations` SET `comment` = :comment WHERE `tableid` = :id");
        //As well as the binding. By using bindParam, and supplying a variable, we're passing it by reference.
        //So whenever it changes, we don't need to bind again.
        $stmt->bindParam(":comment", $comment, PDO::PARAM_STR);
        $stmt->bindParam(":id", $id, PDO::PARAM_INT);
        foreach ($_POST['comment'] as $index => $comment) {
            //All that's left is to set the ID, see how we're reusing the $index of the comment input?
            $id = $_POST['tableid'][$index];
            $stmt->execute();
        }
    }

<textarea name="comment[<?=$f1?>]" cols="25" rows="2"><?=$f2?></textarea>
<?php
$dsn = "mysql:host=xxxx;dbname=xxxxx";
$opt = array(
    PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC
);
$conn = new PDO($dsn, $username, $password, $opt);
$sql  = "UPDATE reservations SET comment=? WHERE tableid= ?";
$stmt = $conn->prepare($sql);
foreach ($_POST["comment"] as $id => $comment) {
    if ($comment) {
        $stmt->execute([$comment, $id]);
    }
}

如果使用CASE，速度会快2-3倍，例如查询：

UPDATE website
    SET http_code = CASE id_website
        WHEN 1 THEN 200
        WHEN 2 THEN 201
        WHEN 3 THEN 202
    END,
    link_exists = CASE id_website
        WHEN 1 THEN 1
        WHEN 2 THEN 2
        WHEN 3 THEN 3
    END
WHERE id_website IN (1,2,3)

我在1000行上进行了测试。

准备时间：0.328秒

案例：0.109 s