Question

I’ve seen a few things that find duplicates, but not quite what I am looking for.

I have a table like so

id | timestamp | member_id | scan_time | event_type | badge_id
1  | 2011-4-20 | 5         | 8:00am    | Meeting    | 100
2  | 2011-4-20 | 6         | 8:01am    | Meeting    | 101
3  | 2011-4-20 | 7         | 8:00am    | Meeting    | 102
4  | 2011-4-20 | 5         | 8:00am    | Meeting    | 100

It’s an attendance table, they scan members id badges and it gives that info.

What I need is to be able to run a select that will show me if there are any duplicate badge_ids for each timestamp.

Answer 1

SELECT  timestamp, badge_id
FROM    mytable
GROUP BY
        timestamp, badge_id
HAVING  COUNT(*) > 1