> I'd like to write a query which returns following information regarding > each item: item, date of very first event, very last event. > Is this possible? I think I can write several SELECT queries and > procces them by an application or possibly write some procedure, but > what is better solution?
Something like the below should do it:
SELECT item
, min_date
, min_event
, max_date
, max_event
FROM items
JOIN (SELECT min(date) AS min_date
, event AS min_event
, item
FROM events
GROUP BY item) AS mn USING (item)
JOIN (SELECT max(date) AS max_date
, event AS max_event
, item
FROM events
GROUP BY item) AS mx USING (item);
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