SQL: GROUP Functions

Which of the following is NOT a GROUP BY function?

• MAX

• MIN

• NVL

• AVG

Which of the following functions can be used without GROUP BY clause in SELECT query? (Select all that apply)

• COUNT

• MAX

• MIN

• AVG

Which of the following SELECT query returns the department number with maximum salary compensated to an employee? (Consider the table structure as given)

• SELECT department_id , max(salary ) FROM employees ;

• SELECT department_id , max(salary ) FROM employees GROUP BY department_id ;

• SELECT max(salary ) FROM employees GROUP BY department_id ;

• SELECT max(salary ) FROM employees ;

Which of the following statements are true about the COUNT function?

• The COUNT function counts the number of rows

• The COUNT(*) function counts the number of rows with duplicates and NULL values

• The COUNT(DISTINCT) function counts the number of distinct rows

• COUNT(*) is equivalent to COUNT(ALL)

What are the appropriate data types accepted by GROUP BY functions?

• Nested Tables

• NUMBER

• CLOB

• DATE

A table T_COUNT has 12 number values as 1, 2, 3, 32, 1, 1, null, 24, 12, null, 32, null. Predict the output of the below query.

SELECT COUNT (*) FROM t_count;

• 12

• 6

• 9

• Throws exception because COUNT function doesn't works with NULL values

A table T_COUNT has 12 number values as 1, 2, 3, 32, 1, 1, null, 24, 12, null, 32, null. Predict the output of the below query.

SELECT COUNT (num) FROM t_count;

• 12

• 6

• 9

• Throws exception because COUNT function doesn't works with NULL values

A table T_COUNT has 12 number values as 1, 2, 3, 32, 1, 1, null, 24, 12, null, 32, null. Predict the output of the below query.

SELECT COUNT (ALL num) FROM t_count;

• 12

• 6

• 9

• Throws exception because COUNT function doesn't works with NULL values

A table T_COUNT has 12 number values as 1, 2, 3, 32, 1, 1, null, 24, 12, null, 32, null. Predict the output of the below query.

SELECT COUNT (DISTINCT num) FROM t_count;

• 12

• 6

• 9

• Throws exception because COUNT function doesn't works with NULL values

What happens when the below query is executed in SQL* Plus?

SELECT COUNT() FROM dual;

• Executes successfully and returns no output

• Executes successfully and returns output as '1'

• Throws exception "ORA-00909: invalid number of arguments"

• Throws exception "ORA-00904: "COUNT": invalid identifier" because COUNT function doesn't works with DUAL table