Random musings - Group by

[Edwin Kurian]

Is the Group by clause in a Select statement redundant? Why is it even needed?
Hoping to get your thoughts.

Edwin

[BoxesAndLines]

Because the DBMS requires it.

[Edwin Kurian]

That is what I am trying to understand...Why does the DBMS need it.
Logically if any columns are aggrergated, shouldn't the SQL group by the other columns?
Is there a case where some columns are aggregated, and some of the other columns are not part of the group by?

[slaborda]

It depends on database engine.

Please search in google info about "over partition" clause.
With this you can combine aggregated data with detail data.

Sergi

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