SELECT field WHERE field1='1' AND (field2='2' OR field3='3')
$this->db->select('field'); $this->db->where("field1", 1); $this->db->where("(field2='2' OR field3='3')");
$this->db->where(sprintf("(foo='bar' OR baz='%s')", $this->db->escape_str($this-input->post('whee')))