SELECT
  workQueueSubscriptionID
INTO
  :workQueueSubscriptionID
FROM
  WorkQueueSubscription wq 
WHERE wq.subscriberType = :subscriberType
  AND wq.workQueueID = :workQueueID 
  AND 
  (
    :searchBySubscriberIDInd = '0' 
    OR wq.subscriberID = :subscriberID 
  ) 
  AND 
  (
    :userName IS NULL 
    OR wq.userName = :userName 
  )