PDO fetch 只返回第一行-php问题

PDO fetch returns only first row(PDO fetch 只返回第一行)

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问题描述

我使用以下代码连接数据库，获取Data_length索引列，并根据数据计算数据库大小.

I'm using the following code to make a connection to the database, fetch the Data_length index column, and calculate the database size based on the data.

出于某种原因，PDO 将始终返回0"，这是第一行中 Data_length 索引的值.无论我做什么，我都只得到第一行索引.

For some reason PDO will always return "0", which is the value for the Data_length index in the first row. Whatever I do, I only get the first rows index.

数据库为 MySQL，引擎为 MyISAM.

The database is MySQL, the engine MyISAM.

PHP 版本:5.5.38
MySQL 版本:5.5.50

PHP Version: 5.5.38
MySQL Version: 5.5.50

这是源代码.

<!DOCTYPE html>
<head>
<title></title>
</head>
<body>

<?php
try {
    error_reporting(-1);
    $host_name  = "my_host";
    $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 . "
" . $row["Data_length"];
    } catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}
?>
</body>
</html>

问题描述

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