请教一个查询SQL的写法，谢谢

Question

下面有两个表，一个是订单表，一个是订单详细表，我想查出某天的商品总数，也就是把amount加起来，
订单表和订单详细表相关联的字段是order_id,请教一下这个SQL语句怎么写，谢谢大家order_id    order_date
2          2011-05-16
3          2011-05-16order_product_id   order_id  amount
1                  2         100
2                  3         100

Answer 1

select order_date,sum(amount)
from tb1 A,tb2 B
where A.order_id = B.order_id
group by order_date

Answer 2

select a.order_id,a.order_date,sum(b.amount)
from tb1 A inner join tb2 B
on A.order_id = B.order_id
group by a.order_id,a.order_date

Answer 3

select order_date,sum(amount)
from table1 a inner join table2 b on a.order_id = b.order_id
group by order_date