aggeregate function quiz

Which of the following is an aggregate function in SQL?

• count( )

• group by

• order by

• where

What does the SUM() function do in SQL?

• Counts the number of rows

• Returns the highest value in a column

• Adds up the numeric values in a column

• Returns the average value of a numeric column

Which SQL query will return the average salary from the employees table?

• SELECT AVG(salary) FROM employees;

• SELECT MEAN(salary) FROM employees;

• SELECT TOTAL(salary) FROM employees;

• SELECT AVERAGE(salary) FROM employees;

What does the COUNT(*) function do?

• Counts the number of non-null values in a column

• Counts the number of distinct values in a column

• Counts the total number of rows in a table

• Counts the number of columns in a table

Which SQL function would you use to find the highest value in a numeric column?

• Heights( )

• top( )

• max( )

• largest( )

How can you calculate the total number of distinct departments in the employees table?

• SELECT COUNT(department) FROM employees;

• SELECT COUNT(DISTINCT department) FROM employees;

• SELECT DISTINCT COUNT(department) FROM employees;

• SELECT COUNT(*) DISTINCT FROM employees;

How would you find the total number of unique job titles in the employees table?

• SELECT DISTINCT COUNT(title) FROM employees;

• SELECT COUNT(DISTINCT title) FROM employees;

• SELECT COUNT(UNIQUE title) FROM employees;

• SELECT COUNT(*) FROM employees GROUP BY title;

Which SQL query will return the total number of rows and the sum of the salaries for employees in department 10?

• SELECT COUNT(*), SUM(salary) FROM employees WHERE dno = 10;

• SELECT COUNT(salary), TOTAL(salary) FROM employees WHERE dno = 10;

• SELECT SUM(*), COUNT(salary) FROM employees WHERE dno = 10;

• SELECT COUNT(*), SUM(salary) FROM employees GROUP BY dno = 10;

Which of the following is a correct usage of the GROUP BY clause?

• SELECT name, COUNT(*) FROM employees GROUP BY department;

• SELECT department, COUNT(*) FROM employees GROUP BY department;

• SELECT department FROM employees GROUP BY COUNT(*);

• SELECT COUNT(*) GROUP BY department FROM employees;

What is the difference between the WHERE and HAVING clauses in SQL?

• WHERE filters groups, and HAVING filters rows

• WHERE filters rows, and HAVING filters groups

• Both can be used interchangeably

• WHERE filters after GROUP BY, HAVING filters before