SELECT name, nvl(age, 0) as age
FROM employees;
SELECT name, nvl(department, 'N/A') as department
FROM employees;
SELECT name, nvl(salary, bonus) as total_compensation
FROM employees;
SELECT name, CASE WHEN nvl(salary, 0) > 50000 THEN 'High' ELSE 'Low' END as salary_category
FROM employees;
