Mysql基础2

拼接：

/*连接和使用别名*/
select concat(vend_name,'(',vend_country,')') as vend_title
from venders
order by vend_name;

执行算术计算：

/*quantity*item_price形成一个新列expanded_price*/
select prod_id,
          quantity,
          item_price,
          quantity*item_price as expanded_price
from orderitems
where order_num = 20005;