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    Question

    Which SQL query will correctly calculate the average

    salary of employees in each department and group them by department in a table named 'employees'?
    A SELECT department, AVG(salary) FROM employees GROUP BY department Correct Answer Incorrect Answer
    B SELECT department, SUM(salary) FROM employees GROUP BY department Correct Answer Incorrect Answer
    C SELECT department, AVG(salary) FROM employees Correct Answer Incorrect Answer
    D SELECT AVG(salary) FROM employees GROUP BY department Correct Answer Incorrect Answer
    E SELECT department, COUNT(salary) FROM employees GROUP BY department Correct Answer Incorrect Answer

    Solution

    To calculate the average salary of employees in each department, we need to use the AVG() aggregate function in SQL. The GROUP BY clause is essential here, as it groups the results by department, ensuring the average is calculated for each individual department, not for the entire table. The correct SQL query is: SELECT department, AVG(salary) FROM employees GROUP BY department This query returns the department and the average salary of employees in that department. Why other options are wrong: b) SELECT department, SUM(salary) FROM employees GROUP BY department : This calculates the sum of the salary, not the average. It’s useful when you want the total salary for each department. c) SELECT department, AVG(salary) FROM employees : This query is incomplete because it lacks the GROUP BY clause. Without it, it would give the average salary for the entire table, not by department. d) SELECT AVG(salary) FROM employees GROUP BY department : This query incorrectly places the aggregate function without selecting the department column, which will result in an error or incorrect output. e) SELECT department, COUNT(salary) FROM employees GROUP BY department : This counts the number of salaries in each department, not the average salary.

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