public function from() {
    $this->_from = "
        FROM civicrm_participant {$this->_aliases['civicrm_participant']}
             LEFT JOIN civicrm_relationship contact_a_relation
                        ON (participant_civireport.contact_id = contact_a_relation.contact_id_b )
             LEFT JOIN civicrm_relationship contact_b_relation
                        ON (participant_civireport.contact_id = contact_b_relation.contact_id_a )
             LEFT JOIN civicrm_event {$this->_aliases['civicrm_event']}
                    ON ({$this->_aliases['civicrm_event']}.id = {$this->_aliases['civicrm_participant']}.event_id ) AND
                        {$this->_aliases['civicrm_event']}.is_template = 0
             LEFT JOIN civicrm_contact {$this->_aliases['civicrm_contact']}
                    ON ({$this->_aliases['civicrm_participant']}.contact_id  = {$this->_aliases['civicrm_contact']}.id  )
             {$this->_aclFrom}
             LEFT JOIN civicrm_address {$this->_aliases['civicrm_address']}
                    ON {$this->_aliases['civicrm_contact']}.id = {$this->_aliases['civicrm_address']}.contact_id AND
                       {$this->_aliases['civicrm_address']}.is_primary = 1
             LEFT JOIN  civicrm_email {$this->_aliases['civicrm_email']}
                    ON ({$this->_aliases['civicrm_contact']}.id = {$this->_aliases['civicrm_email']}.contact_id AND
                       {$this->_aliases['civicrm_email']}.is_primary = 1)
             LEFT  JOIN civicrm_phone  {$this->_aliases['civicrm_phone']}
                     ON {$this->_aliases['civicrm_contact']}.id = {$this->_aliases['civicrm_phone']}.contact_id AND
                         {$this->_aliases['civicrm_phone']}.is_primary = 1
      ";