Tell CodeIgniter not to wrap fields in ticks. You do this by passing false
as the second parameter in select()
:
$this->db->select("NULL as ExtraColumn1", false);
From the manual:
$this->db->select() accepts an optional second parameter. If you set it to FALSE, CodeIgniter will not try to protect your field or table names with backticks. This is useful if you need a compound select statement.