Q
Which rule applies to a SELECT with GROUP BY?
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A
All columns must be aggregated
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B
GROUP BY must appear before FROM
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C
Every non-aggregated column in SELECT must appear in GROUP BY
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D
Only numeric columns can be grouped
Correct Answer:
C. Every non-aggregated column in SELECT must appear in GROUP BY
Explanation:
Otherwise Oracle raises ORA-00979: not a GROUP BY expression.
