Connecting MySQL, MariaDB

To configure Yii DB MySQL/MariaDB with a DI container, you need to create config/common/di/db-mysql.php configuration file:

use Yiisoft\Db\Connection\ConnectionInterface;
use Yiisoft\Db\Mysql\Connection;
use Yiisoft\Db\Mysql\Driver;

/** @var array $params */

return [
    ConnectionInterface::class => [
        'class' => Connection::class,
        '__construct()' => [
            'driver' => new Driver(
                $params['yiisoft/db-mysql']['dsn'],
                $params['yiisoft/db-mysql']['username'],
                $params['yiisoft/db-mysql']['password'],
            ),
        ],
    ],
];

Create a file config/common/params.php for common parameters.

use Yiisoft\Db\Mysql\Dsn;

return [
    'yiisoft/db-mysql' => [
        'dsn' => new Dsn('mysql', '127.0.0.1', 'yiitest', '3306', ['charset' => 'utf8mb4']),
        'username' => 'user',
        'password' => 'password',
    ],
];

Create a file config/common/params.php for common parameters with unix socket DSN.

use Yiisoft\Db\Mysql\DsnSocket;

return [
    'yiisoft/db-mysql' => [
        'dsn' => new DsnSocket('mysql', '/var/run/mysqld/mysqld.sock', 'yiitest'),
        'username' => 'user',
        'password' => 'password',
    ],
];

To use more than one database connection you can use class-aliases.

To configure without DI container, you need to follow these steps:

use Yiisoft\Cache\ArrayCache;
use Yiisoft\Db\Cache\SchemaCache;
use Yiisoft\Db\Mysql\Connection;
use Yiisoft\Db\Mysql\Driver;
use Yiisoft\Db\Mysql\Dsn;

// Dsn.
$dsn = new Dsn('mysql', '127.0.0.1', 'yiitest', '3306', ['charset' => 'utf8mb4']);

// PSR-16 cache implementation.
$arrayCache = new ArrayCache();

// Schema cache.
$schemaCache = new SchemaCache($arrayCache);

// PDO driver.
$pdoDriver = new Driver($dsn, 'user', 'password'); 

// Connection.
$db = new Connection($pdoDriver, $schemaCache);