Question

I have a crossreference table owner_meeting_crossref with a column (owner_id) for owner IDs and column (meeting_id) for meeting IDs that the owner has access to.

My php script is sent an array of meetings, and I know the current user ID is $current_user_id. How can I efficiently check that the user (owner) has access to the meeting IDs sent in?

Answer 1

One option would be to fetch the meetings from the list that the user has access to, then calculate the difference.

$meetingStr = implode(',', array_map('intval', $meetings));
$accessibleMeetingQuery = $db->prepare("
    SELECT meeting_id 
      FROM owner_meeting_crossref 
      WHERE owner_id=:uid AND meeting_id IN ($meetingStr)
");
$accessibleMeetingQuery->execute(array(':uid' => $current_user_id));
$accessibleMeetings= $accessibleMeetingQuery->fetchAll(PDO::FETCH_COLUMN);
$inaccessibleMeetings = array_diff($meetings, $accessibleMeetings);

Another would be to do it all from SQL

SELECT m.id 
  FROM meetings AS m
    LEFT JOIN owner_meeting_crossref AS om 
      ON m.id=om.meeting_id AND om.owner_id=:uid
  WHERE m.id IN ($meetingStr)
    AND om.meeting_id IS NULL