摘要: -- 在sql中只有别名时用的是双引号select employee_id,last_name,12*salary as yearSalary from employees;select last_name from employees;select department_id from depar 阅读全文
posted @ 2016-07-23 09:42 牵牛花 阅读(184) 评论(0) 推荐(0)