我正在建立一个数据库,并有一个表格,表格结构如下:
Att1 Att2 Att3 ....
User1
User2
User3
....
我希望每个属性( Att1, At2, Att3,...) 都附着一个布林变量。 类似 :
Att1 No
Att2 No
Att3 Yes
... ...
每个属性都是来自用户的数值分数( 列表首选 ), 但我想要标记每个属性是否真正重要 。 是否有处理这种依赖性的标准方法? 谢谢!!
如果我们能在表格中嵌入记录,那将是件好事。 然而,标准SQL和大多数数据库并不支持这一点(尽管有例外 ) 。
我将使用一致的命名协议, 发明“ IsimentAtt1” 和“ IsimentAtt2” 等字段。 当我这样做时, 我还有这样的协议, 所有“ 是” 变量只使用“ Y” 或“ N” 的值。 如果我想在输出中看到“ 是” 和“ 否 ”, 那么我使用视图进行转换, 或者在应用层中进行转换 。
在我看来,Attrimite 实际上是一个实体调用 ListingPregence ,它有 Id 键、2个属性、Score 和 Is Insportant ,以及一个称为 User 的FK至 用户 。
user rentley 只有一个 > Id 密钥。
简言之,属性没有属性,这意味着你的模型是错误的。
如果属性本身不是重要的话, 属性评分是否重要? 如果没有, 您只需有一个协议, 即 NULL 评分意味着属性不重要 。
否则,您可以为每个属性列添加另一列(布尔) :
Att1 Important1 Att2 Important2 Att3 Important3 ....
User1
User2
User3
....
BTW 属性是固定的吗? I. e. 您是否“ 坚固” 总是 < / 坚固” 具有完全相同的属性? 如果不是, 您最好使用一个 < a href=" "http://en.wikipedia. org/wiki/Entity-atripte-value_model" rel= “ nofollow noreferrer” > EAV 模型 (尽管EAVs 传统上有一些下行模式):
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一个无关紧要的属性可能只是从USER_ATTRIBUTE表格中略去(假设“否”是顶部回答我的问题)。
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