Is it possible to SELECT all data from different tables in one query?

Pseudo-example 1:

$query = $this->db->get('table1');
$query = $this->db->get('table2');
$query = $this->db->get('table3');
return $query->result();

Pseudo-example 2:

$this->db->select('*');
$this->db->from('table1', 'table2', 'table3');
$query = $this->db->get();
return $query->result();

I think the second example is possible. If not, I want to ask how you would do that.