如何在SQL Server中添加标识列？

Question

Here is my table and Id is unique constraint...Now I want to add Identity Column in ID .Can anyone help me how to do it with TSQL. This is existing table.

Answer 1

You can only have 1 Identity Column per Table. So if you don't have one already, Just alter the table and add the Column. Like this

ALTER TABLE YourTableName
ADD IdCol INT IDENTITY(1,1)

Answer 2

You can rename your previous ID column to keep those values if you need them in your application

EXEC sp_rename 'TableName.id', 'oldid', 'COLUMN';

Then add new ID column with Unique constraint as follows

Alter table TableName Add id int identity(1,1) unique not null