订单表和订单号的有关问题
订单表和订单号的问题
做一个订单表，如下
orderid //主键
customerid //用户号
productid //产品号
num //数量
price //价格
...
如果把订单号作为主键的话，一般买东西都是买很多种类，不同数量，我这么做的表一行只能记录一种产品的情况，如果多种产品，应该都属于同一个订单号，但是订单号是主键，不允许重复，那怎么解决？
------解决方案--------------------
做一个表保存每个订单的东西啊。其中的orderid可以作为外键和你整个表对应。
你从3NF开始看起吧……
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