1、查询员工的名字和部门号和年薪，按年薪降序 按名字升序
SELECT last_name,department_id,salary*12*(1+IFNULL(commission_pct,0))年薪
FROM employees
ORDER BY 年薪 DESC,last_name ASC;
2、选择工资不在8000到17000的员工的姓名和工资，按工资降序
SELECT last_name,salary
FROM employees
WHERE salary NOT BETWEEN 8000 AND 17000
ORDER BY salary DESC;
3、查询邮箱中包含e的员工信息，并先按邮箱的字节数降序，再按部门号升序
SELECT *
FROM employees
WHERE email LIKE '%e%'
ORDER BY LENGTH(email) DESC , department_id ASC;
