oracle sql developer practice online free Practice Exam 2025: Latest Questions

Which statement best describes the purpose of a PRIMARY KEY constraint in a relational table?

You need to display unique department IDs from the EMPLOYEES table. Which query accomplishes this?

You want to list employees ordered by salary from highest to lowest, and for equal salaries, by last name A to Z. Which ORDER BY clause is correct?

You need to display each employee's last name in uppercase and the length of that last name. Which SELECT list is correct?

A developer writes the following query to find employees with no commission: SELECT employee_id, commission_pct FROM employees WHERE commission_pct = NULL; Why does this return no rows even when some employees have NULL commission_pct values?

You need to display a list of employees and a derived column STATUS that shows 'HIGH' when salary >= 10000, otherwise 'STANDARD'. Which expression is appropriate?

You want to find each department's total salary, but only show departments where the total salary exceeds 50000. Which query is correct?

You need to show all employees, including those not assigned to a department, and display the department name when available. Which join should you use?

You need a query that lists employees who earn more than the average salary of their own department. Which query satisfies this requirement?

A report must display a numeric column TOTAL formatted as a character string with a leading currency symbol and thousands separators (for example: $12,345). Which approach is best?

You need to list employees whose commission is not specified (unknown). Which WHERE clause condition correctly returns those rows?

You want to return one row per department from EMPLOYEES showing DEPARTMENT_ID and the highest salary in that department. Which query is correct?

In a relational database, which statement best describes a primary key constraint?

A report must display last names in the format "Smith, John" (LAST_NAME, FIRST_NAME) with a comma and a space. Which expression produces the required output?

You need to list all employees, including those without a department, and show their department name when available. Which join should you use?

You want to show each employee's salary and a new column that displays 0 when COMMISSION_PCT is NULL, otherwise shows COMMISSION_PCT. Which expression is best?

You want to return employees who work in departments located in 'Toronto' without using a subquery. Which query is correct?

You need to display department totals but only for departments whose total salary exceeds 100000. Which clause should be used to apply that filter?

You run the following query and get ORA-00979: not a GROUP BY expression. Which change fixes the error? SELECT department_id, job_id, AVG(salary) FROM employees GROUP BY department_id;

You need to sort employees by salary ascending, but ensure that employees with NULL salaries appear LAST. Which ORDER BY clause satisfies this requirement?

You need a report that shows all employees, including those who are not assigned to any department. You must display EMPLOYEE_ID, LAST_NAME, and DEPARTMENT_NAME. Which query meets the requirement?

A query returns too many rows when filtering for department IDs 10, 20, and 30. The developer wrote: SELECT * FROM employees WHERE department_id = 10 OR 20 OR 30; What is the correct way to write the WHERE clause?

You need to display each employee's last name and salary, and a derived column that shows salary increased by 10%. The increased salary must be rounded to the nearest whole number. Which expression should you use in the SELECT list?

You are asked to show a list of employees with a column STATUS that displays: - 'HIGH' when salary >= 10000 - 'LOW' otherwise Which query correctly implements this requirement?

You need a report that shows each department_id and the number of employees in it. Departments with no employees must also appear with a count of 0. Which query produces the correct result?