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问题描述
我需要了解超级键和复合键之间的区别。我发现的例子更加困惑。你能简单地澄清有什么区别?感谢
I need to understand the difference between super key and composite key. The examples I found made more confused. Can you please simply clarify what is the difference? Thanks
推荐答案
超级键唯一标识一行。它可以由一列或多列组成。复合键是由多个列组成的键。
A super key uniquely identifies a row. It could be made up of one column or many. A composite key is a key made of more than one column.
如果超级键由多个列组成,它也是一个复合。
If a Super Key is made of more than one column it is also a composite.
键唯一标识一行它也是一个超级键。
If a composite key uniquely identifies a row it is also a Super key.
我看不到名称'超级键'使用太多:它通常只被称为'唯一键'。
I don't see the name 'Super key' used too much: it's usually just called a 'Unique key'.
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