创建数据库计算字段
拼接两个列,使用concat()函数来实现
select concat(id,name)
from student
order by id;
输出结果为:
concat(id,name)
1luzhaoshan
2liumeidi
3luxinyan
4luchuanhang
使用别名as
select concat(id,name) as student_title
from student
order by id;
输出结果为:
student_title
1luzhaoshan
2liumeidi
3luxinyan
4luchuanhang
select id,item_price,
id*item_price as money
from orderitems
where id = 1;
查找的结果是:
id | item_price | money
1 | 2.5 | 2.5