Question

I have this table, and I want to select all distinct user_id values where there is both an event=’AAAAAAAAAA’ and event =’XXXXXXXXXX’ (i.e. only result should be user_id=123456789)

unique_row_id  user_id          event       event_timestamp
----------------------------------------------------------------
0              123456789        AAAAAAAAAA  2010-01-20 15:00:00
1              123456789        abcdefghij  2010-01-20 15:00:05
2              123456789        XXXXXXXXXX  2010-01-20 15:00:15
3              987654321        AAAAAAAAAA  2010-01-20 16:00:00
4              987654321        abcdefghij  2010-01-20 16:00:05
5              987654321        abcdefghij  2010-01-20 16:00:15
6              111111111        XXXXXXXXXX  2010-01-20 16:01:00
7              111111111        XXXXXXXXXX  2010-01-20 16:01:05
8              111111111        XXXXXXXXXX  2010-01-20 16:01:15

I’ve tried both:

SELECT distinct user_id from mydata where event='AAAAAAAAAA' and event='XXXXXXXXXX'

which gives me an empty result set, and

SELECT distinct user_id from mydata where event='AAAAAAAAAA' or event='XXXXXXXXXX'

which gives me everything. Any suggestions – I’m guessing I need to go down the ‘join’ road here do I?

Answer 1

Try this:

select user_id from mydata where event='AAAAAAAAAAA'
union
select user_id from mydata where event='XXXXXXXXXXX';

This will select both lists (users w/ AAA, users w/ XXX), and then merge them together, removing duplicate rows.

Hope that helps!

Thanks,
Joe