How to connect to multiple databases in Yii2

To connect to multiple databases in the Yii2 framework, you need to do the following:

1. Create two database configuration files in your site’s config. I keep the connections in separate files, and they look like this (example).

Connection to the first database:

return  [
	'class' => 'yiidbConnection',
	'dsn' => 'mysql:host=127.0.0.1;dbname=work_db1',
	'username' => 'root',
	'password' => '',
	'charset' => 'utf8',
	'tablePrefix' => 'tbl_',
];

Connection to the second database:

return  [
	'class' => 'yiidbConnection',
	'dsn' => 'mysql:host=127.0.0.1;dbname=work_db2',
	'username' => 'root',
	'password' => '',
	'charset' => 'utf8',
	'tablePrefix' => 'tbl_',
];

2. In the main config file, register both connections:

'db' => require(__DIR__ . '/db.php'),
'db2' => require(__DIR__ . '/db2.php'),

Retrieve data from the database using a SQL query:

$Query = (new yiidbQuery());
$Command = Yii::$app -> db2;

$data_ar = $Command -> createCommand(
	$Query -> select('*')
	-> from('{{%authitem}}')
	-> createCommand()
	-> getRawSql()
)
-> queryAll();

echo"<pre>";print_r($data_ar);echo"</pre>";