How to create select SQL statement that would produce "merged" dataset from two tables(Oracle DBMS)?
by Roman Kagan
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Published on 2010-06-03T17:34:55Z Indexed on 2010/06/03 17:54 UTC
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Here's my original question: merging two data sets
Unfortunately I omitted some intircacies, that I'd like to elaborate here.
So I have two tables events_source_1 and events_source_2 tables. I have to produce the data set from those tables into resultant dataset (that I'd be able to insert into third table, but that's irrelevant).
events_source_1 contain historic event data and I have to do get the most recent event (for such I'm doing the following:
select event_type,b,c,max(event_date),null next_event_date from events_source_1 group by event_type,b,c,event_date,null
events_source_2 contain the future event data and I have to do the following:
select event_type,b,c,null event_date, next_event_date from events_source_2 where b>sysdate;
How to put outer join statement to fill the void (i.e. when same event_type,b,c found from event_source_2 then next_event_date will be filled with the first date found
GREATLY APPRECIATE FOR YOUR HELP IN ADVANCE.
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