I have a table below (that also has several other columns, but for the purpose of this example, I'll exclude them) where I only want to include the very first instance for each person (unique_id) by date, which is in DATETIME format.
In the past I've used something like:
SELECT *, least(min(date_event), min(date_event)) as min_date FROM table GROUP BY unique_id ,issue, date_event, age_at_event
However, this is still returning multiple records for each person, rather than just the very first instance?
| unique_id | issue | date_event | age_at_event |
|---|---|---|---|
| 1234 | issue_a | 2016-04-01T00:00:00 | 6 |
| 1234 | issue_a | 2016-04-01T00:00:00 | 6 |
| 1234 | issue_b | 2018-04-01T00:00:00 | 8 |
| 5678 | issue_a | 2019-09-01T00:00:00 | 2 |
| 5678 | issue_a | 2021-09-01T00:00:00 | 4 |
| 65431 | issue_c | 2019-09-01T00:00:00 | 1 |
| 1234 | issue_a | 2022-09-01T00:00:00 | 12 |
CodePudding user response：
You can use the 