PHP PDO Data_length始终返回"0". [英] PHP PDO Data_length always returns "0"
问题描述
好吧，我现在正在尝试以下两个小时左右，但无法正常工作.以下代码将始终返回"0".请，任何人都可以看到问题出在哪里.这应该是一种魅力.在PhpMyAdmin中，当我运行该语句时，它可以正常工作.
Well, I'm just trying the following for around two hours now and I can't get it to work. The following code will always return "0". Please, can anyone see where is the problem. This should work as a charm. And in PhpMyAdmin, when I run the statement it works correctly.
实际上，这是此处有关SO的另一个问题的复制/粘贴代码，已被接受为有效答案.在此处中进行检查.
Actually, this is a copy/pasted code from another question here on SO which was accepted as a working answer. Check it out here.
使用以下命令不会引发任何错误:
error_reporting(-1);和
PDO::ERRMODE_EXCEPTION.
No errors are thrown using:
error_reporting(-1); and
PDO::ERRMODE_EXCEPTION.
更新:
绝对，我从查询中仅获得第一行，其中Data_lenght为"0".我还测试了fetchAll，并且还在尝试访存时尝试访问Data_length索引.没有运气.
UPDATE:
Definitely, I'm getting only the first row from the query where the Data_lenght is "0". I've tested also fetchAll, and also trying to access the Data_length index while fetching. No luck.
<!DOCTYPE html>
<head>
<title></title>
</head>
<body>
<?php
try {
error_reporting(-1);
$host_name = "my_hsot";
$database = "my_db";
$user_name = "my_user";
$password = "my_pwd";
$conn = new PDO("mysql:host=$host_name;dbname=$database", $user_name, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sth = $conn->query('SHOW TABLE STATUS');
$dbSize = 0;
$row = $sth->fetch(PDO::FETCH_ASSOC);
$dbSize = $row["Data_length"];
$decimals = 2;
$mbytes = round($dbSize/(1024*1024),$decimals);
echo $dbSize . "\n" . $row["Data_length"];
} catch (PDOException $e) {
echo 'Connection failed: ' . $e->getMessage();
}
?>
</body>
</html>
感谢您的帮助.
推荐答案
PDO始终返回"0"，因为$row = $sth->fetch(PDO::FETCH_ASSOC);仅返回查询的第一行，而Data_length的索引为"0"，因为它可以是任何其他值.
PDO always returns "0" because $row = $sth->fetch(PDO::FETCH_ASSOC); returns only the first row from the query, and the index of Data_length there is "0", as it could be any other value.
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