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Home Backend Development PHP Tutorial Why does my PHP database connection fail?

Why does my PHP database connection fail?

Jun 05, 2024 pm 07:55 PM
php Database Connectivity

PHP database connection fails due to the following reasons: the database server is not running, the host name or port is incorrect, the database credentials are incorrect, or the appropriate permissions are missing. Solutions include: starting the server, checking the hostname and port, verifying credentials, modifying permissions, and adjusting firewall settings.

為什么我的 PHP 數(shù)據(jù)庫連接失?。?></p>
<p><strong>#Why does my PHP database connection fail? </strong></p>
<p><strong>Introduction</strong></p>
<p>It is common to encounter errors when connecting to a database using PHP. This article describes common problems connecting to databases and their solutions. </p>
<p><strong>Common Errors</strong></p>
<ul>
<li><strong>Unable to connect to the MySQL server. </strong></li>
<li><strong>The host is unreachable. </strong></li>
<li><strong>Access to the database is denied. </strong></li>
</ul>
<p><strong>Cause</strong></p>
<p>These errors may have the following causes:</p>
<ul>
<li>The database server is not running or is inaccessible. </li>
<li>The hostname or port is incorrect. </li>
<li>The database credentials (username, password) are incorrect. </li>
<li>Lack of appropriate permissions. </li>
</ul>
<p><strong>Practical case</strong></p>
<p><strong>Error: </strong>Unable to connect to the MySQL server. </p>
<p><strong>Cause: </strong>The database server is not running. </p>
<p><strong>Solution: </strong>Start the MySQL server. </p>
<p><strong>Code sample:</strong></p><pre class='brush:php;toolbar:false;'><?php

// 檢查 MySQL 服務(wù)器是否已啟動(dòng)
$mysqli = new mysqli("localhost", "root", "password");

// 如果連接失敗,打印錯(cuò)誤信息
if ($mysqli->connect_errno) {
  echo "Failed to connect to MySQL: " . $mysqli->connect_error;
} else {
  echo "Connected to MySQL successfully!";
}

?></pre><p><strong>Other solutions</strong></p>
<ul>
<li>
<strong>Host unreachable:</strong> Check that the hostname or IP address is correct. </li>
<li>
<strong> Access to the database is denied: </strong> Check the database credentials and ensure you have the appropriate permissions. </li>
<li>
<strong>Lack of appropriate permissions: </strong>Modify database user permissions to grant them access to the database. </li>
<li>
<strong> Firewall restrictions: </strong> Check whether the firewall settings allow communication with the database server. </li>
</ul><p>The above is the detailed content of Why does my PHP database connection fail?. For more information, please follow other related articles on the PHP Chinese website!</p>


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