system/Database/Database.php
public function load(array $params = [], string $alias)
	{
		// No DB specified? Beat them senseless...
		if (empty($params['DBDriver']))
		{
			throw new \InvalidArgumentException('You have not selected a database type to connect to.');
		}

		$className = strpos($params['DBDriver'], '\\') === false
			? '\CodeIgniter\Database\\' . $params['DBDriver'] . '\\Connection'
			: $params['DBDriver'] . '\\Connection';

		$class = new $className($params);

		// Store the connection
		$this->connections[$alias] = $class;

		return $this->connections[$alias];
	}
public function load(array $params = [], string $alias)
	{
		// No DB specified? Beat them senseless...
		if (empty($params['DBDriver']))
		{
			throw new \InvalidArgumentException('You have not selected a database type to connect to.');
		}

		$className = strpos($params['DBDriver'], '\\') === false
			? '\CodeIgniter\Database\\' . $params['DBDriver'] . '\\Connection'
			: $params['DBDriver'] . '\\Connection';

		$class = new $className($params);

		// Store the connection
		$this->connections[$alias] = $class;

		return $this->connections[$alias];
	}
Parses the connection binds and returns an instance of
the driver ready to go.

@param array  $params
@param string $alias

@return   mixed
@internal param bool $useBuilder