CREATE TABLE employees (first_name VARCHAR, last_name VARCHAR, salary INT, department_id VARCHAR)

display the department ID, full name (first and last name), salary for those employees who is highest salary in every department.
SELECT first_name, last_name, salary, department_id, MAX(salary) FROM employees GROUP BY department_id
SELECT "first_name", "last_name", "salary", "department_id", MAX("salary") FROM "employees" GROUP BY "department_id"