CodeIgniter中MAMP环境下数据库主机配置报错及配置方法咨询

First, let's clear up the core confusion here: you're mixing up two entirely separate ports—your web server's port (81) and your MySQL database's port (3307). The localhost:81 is the address you use to access your website in a browser, not the address MySQL listens on. That's exactly why you're getting the "Unknown MySQL server host" error: MySQL doesn't recognize "localhost:81" as a valid database host.

Correct Configuration for database.php #

You need to specify the MySQL host and port separately. MAMP runs MySQL on port 3307, so we'll define that explicitly, while keeping the hostname as a standard local database address. Here's the working setup:

$db['default'] = array(
    'dsn'   => '',
    'hostname' => 'localhost', // Use '127.0.0.1' if you hit socket-related issues
    'username' => 'root', // Default MAMP MySQL username
    'password' => 'root', // Default MAMP MySQL password
    'database' => 'your_actual_db_name', // Replace with your database name
    'dbdriver' => 'mysqli',
    'dbprefix' => '',
    'pconnect' => FALSE,
    'db_debug' => (ENVIRONMENT !== 'production'),
    'cache_on' => FALSE,
    'cachedir' => '',
    'char_set' => 'utf8',
    'dbcollat' => 'utf8_general_ci',
    'swap_pre' => '',
    'encrypt' => FALSE,
    'compress' => FALSE,
    'stricton' => FALSE,
    'failover' => array(),
    'save_queries' => TRUE,
    'port' => 3307, // Critical: MAMP's MySQL port goes here
);

Why This Works #

• The hostname (localhost or 127.0.0.1) points directly to your local MySQL server, no web port needed here.
• The port parameter tells CodeIgniter to connect to MySQL on 3307 instead of the default 3306.
• Your web server's 81 port only matters when accessing your site in the browser (e.g., http://localhost:81/your_ci_project)—it has zero impact on how the app connects to the database.

Quick Troubleshooting Note #

If localhost still causes issues, switch to 127.0.0.1 as the hostname. Sometimes localhost tries to use a Unix socket instead of TCP/IP, which might not align with MAMP's MySQL configuration.

内容的提问来源于stack exchange，提问作者Yuva Ammu