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Oracle ROWNUM, paging, 三层嵌套,分页

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迄今为止网上见到的能让我很好理解ROWNUM的一段话:
Oracle's ROWNUM is a sequence number generator. It always starts with 1. The sequence numbers are assigned to each row as they are selected. So when you say "ROWNUM > 1" , you are implicitly asking oracle to assign rownumbers starting from 2, which it cannot do and so you wouldn't get any rows. For testing, try "ROWNUM >=1" where you are asking the rownum to be assigned from 1 and all the rows will get selected.

Summary: Any condition which involves "ROWNUM" should ask Oracle to start assigning rownumbers starting from "1". All other conditions fail.
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