mysql-字段别名

select 
name n,
age as age
from ...

mysql中的where子句不能使用字段别名

查询姓名和年薪

USE hr;
SELECT employee_id,CONCAT(first_name,' ',last_name) NAME,salary*12 anual_salary
FROM employees;

查询姓名和年薪按年薪大于100000的

USE hr;
SELECT employee_id,CONCAT(first_name,' ',last_name) AS NAME,salary*12 AS anual_salary
FROM employees
WHERE salary*12>100000;