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Huh - I guess I never thought about it. It makes sense to disallow it, though - column aliases are there to rename complex expressions, which you probably _sho
by commandlinefan 7y ago
Huh - I guess I never thought about it. It makes sense to disallow it, though - column aliases are there to rename complex expressions, which you probably _shouldn't_ be grouping on anyway.
- tempguy9999 7y agoI think it's for other reasons (and grouping on expressions is quite reasonable anyway). It's (IIRC!) something to do with the situation of select x + y as x from ... group by x which x are we talking about? (Logically that example is crap because only the alias x makes sense, but something like that anyway).
- yellowapple 7y ago> which you probably _shouldn't_ be grouping on anyway. This is frequently unavoidable, though. Or more precisely: it could be avoided with a sane database design, but the databases on which I have to work for my day job are the precise opposite of "well-designed", so grouping on complex expressions is unfortunately an inevitability.
- commandlinefan 7y agoThat's true - I can definitely imagine having to group on something like "concat(lastname + ', ' + firstname)".