问题描述
在SQL Server数据库中,主键和标识列之间有什么区别?列可以是主键,而不是缩进。然而,列不能成为一个身份而不是主键。
In a SQL Server db, what is the difference between a Primary Key and an Identity column? A column can be a primary key without being an indentity. A column cannot, however, be an identity without being a primary key.
除了差异之外,PK和Identity列提供的只是一个PK列吗?
In addition to the differences, what does a PK and Identity column offer that just a PK column doesn't?
编辑:糟糕。如下所述,现在由我验证,列可以是身份,而不是PK。当我测试这个,我的列类型是一个字符串,我无法将其设置为一个身份。
edit: Oops. As pointed out below and now verified by me, a column can be an identity without being a PK. When I tested this, my the column type was a string and I was unable to set it to an identity. Makes sense.
推荐答案
一列不一定是PK,肯定是一个身份。
A column can definitely be an identity without being a PK.
身份只是一个自动增加列。
An identity is simply an auto-increasing column.
主键是定义行的唯一列或列。
A primary key is the unique column or columns that define the row.
这两个经常一起使用,但不要求这样做。
These two are often used together, but there's no requirement that this be so.
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