Getting a list of subsequence values in SQL

Question

I have the following scenario and I am not sure if it is possible to implement it using SQL.

UID	PID	Event	Timestamp
323	1	A	10:01
323	1	B	10:02
323	1	C	10:03
323	1	D	10:04
321	3	A	10:03
321	3	B	10:04
321	3	C	10:05

I need to get the subsequence of events following the event 'B' so the result will be something like :

UID	PID	list of events
323	1	C,D
321	3	C

Thank you in advance for your help

Answer 1

I know how to do this for MySQL and have a fiddler example here: http://sqlfiddle.com/#!9/ee6809/12

SELECT
   UID, a.PID, GROUP_CONCAT(EVENT)
FROM 
TableName AS a
LEFT Join (SELECT PID, eventtime FROM TableName WHERE event = 'B') b on a.PID = b.PID
WHERE a.eventtime > b.eventtime
GROUP BY UID, PID

Which would be the general concept for me. But redshift doesn't have GROUP_CONCAT so looking at this other post I think you can use listagg Group Concat in Redshift