Examine the description of the STUDENTS table: STD_ID NUMBER(4) COURSE_ID VARCHAR2(10) START_DATE DATE END_DATE DATE Which two aggregate functions are valid on the START_DATE column? (Choose two.)

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  1. SUM(start_date)

  2. AVG(start_date)

  3. COUNT(start_date)

  4. AVG(start_date, end_date)

  5. MIN(start_date)

  6. MAXIMUM(start_date)

Show answer
Correct Option: C,E

AI Explanation

To answer this question, let's go through each option to determine which aggregate functions are valid on the START_DATE column:

Option A) SUM(start_date) - The SUM function is used to calculate the sum of numerical values. However, the START_DATE column is of type DATE, not a numerical value. Therefore, this option is incorrect.

Option B) AVG(start_date) - The AVG function is used to calculate the average of numerical values. Since the START_DATE column is of type DATE, this option is incorrect.

Option C) COUNT(start_date) - The COUNT function is used to count the number of rows or non-null values in a column. This function is valid for the START_DATE column since it counts the number of occurrences of the column values. Therefore, this option is correct.

Option D) AVG(start_date, end_date) - The AVG function calculates the average of numerical values. However, in this option, there are two columns provided (START_DATE and END_DATE), which is not valid for the AVG function. Therefore, this option is incorrect.

Option E) MIN(start_date) - The MIN function is used to find the minimum value in a column. Since the START_DATE column is of type DATE, this option is valid.

Option F) MAXIMUM(start_date) - The MAXIMUM function is not a valid aggregate function in SQL. Therefore, this option is incorrect.

The correct answers are C) COUNT(start_date) and E) MIN(start_date) because both functions are valid for the START_DATE column.

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