题解 | 获取当前薪水第二多的员工的emp_no以及其对应的薪水salary

SELECT
    em.emp_no,
    sa.salary,
    em.last_name,
    em.first_name
FROM
    employees em
    JOIN salaries sa USING (emp_no)
WHERE
    salary in (
        SELECT
            MAX(salary)
        FROM
            salaries
        WHERE
            salary < (
                SELECT
                    MAX(salary)
                FROM
                    salaries
            )
    )
	
	SELECT emp_no, salary, last_name, first_name
FROM(
    SELECT em.emp_no, sa.salary, em.last_name, em.first_name,
    DENSE_RANK() OVER(ORDER BY sa.salary DESC) rk
FROM employees em 
JOIN salaries sa USING(emp_no)
) co 
WHERE rk = 2;