Why Can\'t I Connect to My Database in CodeIgniter After Switching to MySQLi?

Unable to Connect to Database Server: Diagnosing the Issue in CodeIgniter

When attempting to switch from the MySQL driver to the MySQLi driver in CodeIgniter, you might encounter the error message "Unable to connect to your database server using the provided settings." To troubleshoot this issue and resolve the problem effectively, consider the following steps:

Start by examining your database configuration settings in the config/database.php file. Replace 'MySQL' with 'MySQLi' and specify the port number (e.g., 3306) in the $db['default']['dbdriver'] and $db['default']['port'] settings respectively.

After updating the configuration, add the following code at the end of the config/database.php file to debug the database connection:

...
...
echo '<pre class="brush:php;toolbar:false">';
print_r($db['default']);
echo '

'; echo 'Connecting to database: ' .$db['default']['database']; $dbh=mysql_connect ( $db['default']['hostname'], $db['default']['username'], $db['default']['password']) or die('Cannot connect to the database because: ' . mysql_error()); mysql_select_db ($db['default']['database']); echo '
Connected OK:' ; die( 'file: ' .__FILE__ . ' Line: ' .__LINE__);

This code will display detailed information about the database connection settings and attempt to establish a connection. If the connection fails, it will output an error message indicating the root cause of the issue.

Review the output to identify the problem. It could be a typo in the hostname, username, or password, a port mismatch, or an issue with the database server itself.

If the above steps do not resolve the problem, consider the following additional possibilities:

• Check your PHP configuration to ensure that the PHP MySQLi extension is enabled.
• Verify that the MySQL server is running and listening on the correct port.
• Inspect the database user's permissions to ensure that they have the necessary privileges to access the database.

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