First unsubscribe occurrence for the subscriber on this job.
Example query
SELECT TOP 100
JobID, SubscriberKey, SubscriberID, EventDate, ListID, BatchID
FROM _Unsubscribe
WHERE EventDate >= DATEADD(day, -30, GETDATE())
ORDER BY EventDate DESC
Valid in Query Studio and Automation Studio Query Activities. GROUP BY is only needed for aggregates; ORDER BY is optional but recommended with TOP so rows are meaningful. Narrow date ranges on large tracking views to avoid timeouts.