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Question 8: Aggregate Functions

Examine the description of the STUDENTS table:
STD_ID NUMBER(4)
COURSE_ID VARCHARD2(10)
START_DATE DATE
END_DATE DATE

Which two aggregate functions are valid on the START_DATE column? (Choose two)

A. SUM(start_date)

B. AVG(start_date)

C. COUNT(start_date)

D. AVG(start_date, end_date)

E. MIN(start_date)

F. MAXIMUM(start_date)


Answer: C & E


Explanation:
It is possible to apply COUNT() and MIN() functions on the column with DATE data type.


Incorrect Answers
A: Function SUM() cannot be used with DATE data type column.

B: Function AVG() cannot be used with DATE data type column.

D: Function AVG() cannot be used with DATE data type column, and function AVG() just has one parameter X, not two. It averages all X column values returned by the SELECT statement.

F: There is no MAXIMUM() function in Oracle, only MAX() function exists.
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