GROUP BY dept_name;
A. Dept_id should not be used in group by clause
B. Group by clause is not valid in this query
C. Avg(salary) should not be selected
D. None
Answer:A
GROUP BY dept_name;
A. Dept_id should not be used in group by clause B. Group by clause is not valid in this query C. Avg(salary) should not be selected D. None
Explanation: Any property that does not occur in the group by clause must only appear in an aggregate function if it also appears in the select clause; otherwise, the query is considered incorrect.