Oracle SQL Developer comparing rows

Question

I am using Oracle SQL Developer, Version 4.0.0.13, Build MAIN-13.80

I have interesting problem, my query returns to me big amount of data with priority (1 to 4) and date/time. What I have to accomplish is to delete all rows from table that has priority 4 AND that next event that occurred was in 5 minutes time frame from previous with priority 1-3.

Maybe it sounds confusing, but see data below

           Date            Priority 
 - 2013-03-28 21:42:08        4 

 - 2013-03-28 21:45:20        1

 - 2013-03-28 21:45:16        1 

 - 2013-03-28 21:46:37        1

So from here, I would like to delete first row, because it has priority 4 and because next event that happen was in 5 minute time frame and it was in (1,2,3). In case next row was also priority 4, we just ignore it and move on.

In table I have column for Date , Priority and RowID so how can I check row after priority 4 and compare dates to see 5 minutes difference, and of course everything is sorted by date asc?

Thank you

Answer 1

It sounds like you want something like

DELETE FROM table_name a
 WHERE priority = 4
   AND EXISTS( SELECT 1
                 FROM table_name b
                WHERE b.priority IN (1,2,3)
                  AND b.id != a.id
                  AND b.dt BETWEEN a.dt AND a.dt + interval '5' minute )

I'm assuming that your column names aren't actually rowid and date since those are reserved words. I'm using id and dt instead.