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Random musings - Group by

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Kimball Forum :: Topics :: ETL and Data Quality

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Post  Edwin Kurian Wed Feb 18, 2009 11:22 am

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

Edwin

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Post  BoxesAndLines Wed Feb 18, 2009 2:27 pm

Because the DBMS requires it.
BoxesAndLines
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Post  Edwin Kurian Wed Feb 18, 2009 6:03 pm

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?

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Post  slaborda Wed Feb 18, 2009 6:46 pm

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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