SQL Server 向现有表添加自动增量主键

SQL Server add auto increment primary key to existing table(SQL Server 向现有表添加自动增量主键)

问题描述

作为标题，我有一个已经填充了 150000 条记录的现有表.我添加了一个 Id 列(当前为空).

As the title, I have an existing table which is already populated with 150000 records. I have added an Id column (which is currently null).

我假设我可以运行查询来用增量数字填充此列，然后设置为主键并打开自动增量.这是正确的方法吗?如果是这样，我该如何填写初始数字?

I'm assuming I can run a query to fill this column with incremental numbers, and then set as primary key and turn on auto increment. Is this the correct way to proceed? And if so, how do I fill the initial numbers?

推荐答案

不 - 你必须反过来做:从一开始就把它添加为 INT IDENTITY - 它会是执行此操作时填充标识值:

No - you have to do it the other way around: add it right from the get go as INT IDENTITY - it will be filled with identity values when you do this:

ALTER TABLE dbo.YourTable
   ADD ID INT IDENTITY

然后您可以将其设为主键:

and then you can make it the primary key:

ALTER TABLE dbo.YourTable
   ADD CONSTRAINT PK_YourTable
   PRIMARY KEY(ID)

或者如果您更喜欢一步完成所有操作:

or if you prefer to do all in one step:

ALTER TABLE dbo.YourTable
   ADD ID INT IDENTITY
       CONSTRAINT PK_YourTable PRIMARY KEY CLUSTERED

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