Why Oracle does not support "group by 1,2,3"? [closed]
Actually, when you go by common sense, column aliases can be used in a ORDER BY or a outer query only. Because, when you do a ORDER by, it happens only after the rows selection, by that time the alias is available. But during a GROUP BY, only after the grouping the selection is done, so until grouping is completed, oracle unaware of the column aliases.
i think, it is pretty much straight forward. may be other DBMS support them, implementing some SQL preprocessing.
So, in short, since the SELECT happens only after GROUP BY, and as column aliases are made only in SELECT, oracle dont support it! The programmer too, when understood this, may not have a need for wanting column aliases in grouping. Atleast me.