Typically, whatever query works in database, can be used in QV script.
I had some problems with the long fields, although it wasn't Oracle. Used this:
NotesPart1 & NotesPart2 & NotesPart3 & NotesPart4 as FullNotes,
substring(LONGNOTES,1, 8000) as NotesPart1,
substring(LONGNOTES,8001, 16000) as NotesPart2,
substring(LONGNOTES,16001, 24000) as NotesPart3,
substring(LONGNOTES,24001, 32000) as NotesPart4,
Thanks Michael for the suggestion, that worked for me, although it does have a fixed limit depending on how many chunks we query for that we will have to be aware of.
I had the problem of trying to query a table where one of the fields was a CLOB containing around 5000 characters of text defining a long list of properties. When loaded into Qlikview this large field was being truncated and I only had the fist 4k (4096) chars of text in the Qlikview field and many of the properties were not being loaded.