The primary component required in order to work with databases is the yii\db\Connection class. Through this class, we can connect to a variety of different database types, ranging from local SQLite databases to clustered MySQL databases. The simplest way to establish a connection to a database is to create a SQLite database connection, as follows:
$connection = new \yii\db\Connection([
'dsn' => 'sqlite:/' . \Yii::getAlias('@app') . '/runtime/db.sqlite',
'charset' => 'utf8'
]);
$connection->open();Normally, however, we'll want to use a single database connection across our entire application. We can keep our application DRY by putting our database configuration into the db component of our web or console configuration file. Following the examples laid out in the previous chapters, this component will reference the config/env/<ENV>/db.php file. As an example, establishing a SQLite connection in this file will be done as follows:
<?php return...