php - 我无法连接到mysql

Question

我已经在az.pl上创建了一个数据库，我想使用在其他网站上完美运行的旧代码。我收到此错误消息：


  无法连接到MySQL


这是我的代码：

$dbh = mysqli_connect("localhost","user","password", "db") or die ("could not connect to mysql");

我也尝试过：

$c = mysql_connect("localhost", "user", "password");
mysql_select_db("db");
$result = mysql_query("SELECT 'Hello, dear MySQL user!' AS _message FROM DUAL");
$row = mysql_fetch_assoc($result);
echo htmlentities($row['_message']);

两者具有相同的结果，错误消息。

我已经在网上搜索过，但没有找到确切的问题。

Answer 1

在调试连接问题时，请考虑遵循以下文档：

http://php.net/manual/en/function.mysqli-connect.php

<?php
$link = mysqli_connect("localhost", "user", "password", "db");

if (!$link) {
    echo "Error: Unable to connect to MySQL." . PHP_EOL;
    echo "Debugging errno: " . mysqli_connect_errno() . PHP_EOL;

    // this will tell you why the connection failed
    echo "Debugging error: " . mysqli_connect_error() . PHP_EOL;

    exit;
}

echo "Success: A proper connection to MySQL was made! The my_db database is great." . PHP_EOL;
echo "Host information: " . mysqli_get_host_info($link) . PHP_EOL;

mysqli_close($link);
?>