8i or 9i

I am having a problem in deciding as to which book that I need to follow for learning oracle. The problem is that in my college coursework we have to learn oracle 8i. But I would like to go for 9i, can anybody tell me the differences between 8i and 9i. And also possibly suggestions on books. Is 8i a subset of 9i? I think that if one knows 8i, 9i would be a sort of natural progression.

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Imanpreet Singh Arora

imanpreet_arora AT yahoo DOT co DOT in