Daten zusammenfassen mit Aggregatsfunktionen

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Zu den Möglichkeiten der Oracle Aggregatsfunktionen wie

group by
rollup
cube
grouping sets

aber auch den analytischen Funktionen gibt es bei der APEX-Community einen sehr guten und kompakten Überblick:

http://www.oracle.com/webfolder/technetwork/de/community/apex/tipps/aggregateFunctions/index.html

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