求助：PHP MySQLi连接报错（HY000/2002）及无法获取mysqli问题

Hey there! Let's work through these errors step by step. The root problem here is your script can't establish a connection to the MySQL server—all the follow-up errors on lines 7 and 23 are just side effects of that failed initial connection.

What's causing the "No such file or directory" error? #

When you use localhost as the host in MySQLi, PHP tries to connect using a Unix socket file instead of standard TCP/IP. If that socket file doesn't exist in the location PHP expects (super common on systems like Synology NAS, given your /volume1/web path), you get this exact error.

Quick Fixes to Try #

1. Force TCP/IP Connection (Simplest Solution)

Replace localhost with 127.0.0.1 in your connection line. This tells PHP to skip the socket file and use TCP/IP directly, which avoids the "no such file" issue:

<?php 
// Connect to the DB 
$mysqli = NEW MySQLi("127.0.0.1","root","","dbproject"); 

// Add a connection check first to catch issues early
if ($mysqli->connect_error) {
    die("Connection failed: " . $mysqli->connect_error);
}

//Query the DB 
$resultSet = $mysqli->query("SELECT * FROM clients"); 
// Count the returned rows 
if($resultSet->num_rows != 0) { 
    while($rows = $resultSet->fetch_assoc()) { 
        $id = $rows['id']; 
        $fname = $rows['firstname']; 
        $lname = $rows['lastname']; 
        $country = $rows['country']; 
        echo "<p>ID: " .$id. " <br /> Name: ".$fname." ".$lname. "<br /> Country: ".$country." </p>"; 
    } 
} else{ 
    echo "No records found in the clients table."; 
} 

// Clean up the connection when done
$mysqli->close();
?>

2. Specify the Correct Socket Path

If you need to keep using localhost, you'll need to point PHP to the actual location of your MySQL socket file:

• Create a temporary phpinfo.php file with this code: <?php phpinfo(); ?>
• Run it in your browser and look for the mysqli.default_socket value (e.g., /run/mysqld/mysqld.sock on Synology)
• Add that socket path to your connection line:

$mysqli = NEW MySQLi("localhost","root","","dbproject", null, "/path/to/your/mysqld.sock");

Additional Checks to Rule Out Other Issues #

Don't forget to verify these basics too:

• Is the MySQL/MariaDB service actually running on your server?
• Is the root password correct? Your script uses an empty password—double-check that matches your server's setup.
• Does the dbproject database exist? You can confirm this via phpMyAdmin or the MySQL command line.

Once you fix the connection problem, the errors on lines 7 and 23 will disappear automatically—they only happen because the $mysqli object wasn't created successfully.

内容的提问来源于stack exchange，提问作者R. Bos