Mike Yearwood
Toronto, Ontario, Canada
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Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
>I'm upgrading a VFP7 app to VFP9. I understand that all non-agregate fields should be included in the GROUP BY clause. Am I mistaken to assume that the primary group should be listed first? If the other fields are included only to make the select work, does it matter whatorder they are listed in?
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>Is there a downside to listing many fields in the GROUP BY clause?
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>Is there a better (or proper) way to handle this?
I believe the suggestions to use min and max on non-aggregate fields is not really good practice. IMO it's basically a workaround. What exactly does MAX(REP_NAME) mean?
I think, most of the time, you should either do your sums in a separate query order as a subtable and use joins to put everything together.
select ;
rep_pk, ;
rep_id, ;
rep_name, ;
gross_sales.gross_amount ;
from salesreps ;
inner join ;
(select sal_repfk, sum(sal_amount) as gross_amount from sales group by sal_repfk) gross_sales ;
on sal_repfk = rep_pk
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