If you don't need a particular table information, having it on the view is useless... So if you have the need of a distinct rescult set only one view would not handle this. So the on the fly generated query is not better than the view because it's better optimzed than a view would be, but because it's a diferent query.

All of which is true, but it is also true that the optimiser doesn't always work out that some of the stuff returned by the view is never used by a particular query that calls the view, and that therefore it doesn't need to be calculated. (To put it very very crudely.)

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Tim Ward