For example I have this table events:
| user_id | event_type | date_of_event |
|---|---|---|
| userA | X | 01-01-2000 |
| userA | Y | 01-01-2005 |
| userB | X | 01-01-2000 |
| userB | Y | 01-01-2100 |
I want to select all users that have an event_type = X but no event_type Y in the next 2 years AFTER the date of event_type X. So in the table above that would be userA and userB
I know I can do this in 2 mysql queries but was just wondering if there is a way to do this in just 1 query
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Answer
You can do it with a self-join.
SELECT DISTINCT a.user_id
FROM yourTable AS a
LEFT JOIN yourTable AS B
ON a.user_id = b.user_id AND b.date_of_event < DATE_ADD(a.date_of_event, INTERVAL 2 YEAR)
AND b.event_type = 'Y'
WHERE a.event_type = 'X'