CiviCRM Community Forums (archive)

The SQL generated when a Relationship (the Views kind, not the Civi kind) is added to a Campaign within a Activity-based View is incorrect:
LEFT JOIN {civicrm_campaign} civicrm_campaign_civicrm_activity ON civicrm_activity.id = civicrm_campaign_civicrm_activity.id
It should be:
LEFT JOIN {civicrm_campaign} civicrm_campaign_civicrm_activity ON civicrm_activity.campaign_id = civicrm_campaign_civicrm_activity.id
That is, the civicrm_activity field that links to civicrm_campaign should be "campaign_id" and not "id".
The problem comes from 
civicrm/drupal/modules/views/components/civicrm.core.inc line 1701 (the $data['civicrm_activity']['campaign_id']['relationship'] array).  Changing:
'field' => 'id',
to
'field' => 'campaign_id',
produced the expected SQL, and allowed the View to display the correct campaign information associated with an activity.
This required clearing the Drupal cache in order for the change to be picked up by Views.
(Drupal 7.23, Civi 4.3.4)