Show first record for series of unique identifiers

I have a table that includes the following fields

• trackingNo
• event
• timestamp

I am trying to find the first event, based on timestamp, for a series of tracking numbers. I know I can pull all events for specific tracking numbers using the following.

SELECT trackingNo, timestamp
FROM t
WHERE trackingNo in ("122345", "67890", "24680:)

This would return the following results

How do I return just the first record for each tracking number based on timestamp? I want the results to show

I’ve tried TOP and HAVING MIN but that only returned one result.

>Solution :

Min to get the earliest timestamp and group by to get one for each of the tracking numbers.

  SELECT trackingNo
       , MIN(timestamp) timestamp
    FROM t
   WHERE trackingNo in ("122345", "67890", "24680:)
GROUP BY trackingNo