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Archives of the TeradataForum
Message Posted: Thu, 22 May 2003 @ 15:20:37 GMT
| Subj: | | Re: Time Stamp in Teradata |
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| From: | | Geoffrey Rommel |
| | So if you select without ORDER BY you'll always end upwith an unordered result set. This is different to mostother RDBMSes. | |
I hesitate to disagree with Dieter, but this is not quite correct. In relational theory, relations are sets, so they are unordered.
For instance, the set {integers between 1 and 20} can be enumerated in a conventional order -- 1, 2, 3, etc. -- but there is no order to the
set itself; all 20! enumerations specify the same set. In other RDBMSes, the rows may in fact come out in the same order every time, but
this is merely a by-product of the physical ordering on disk; it does not imply that there is an order to the rows of the table.
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