As I understood in normal cases we are creating a table with Primary key which is having Identity property So Rename or Delete a column which is associated with Primary Key constraint will not be possible because constraint Rules are validating column structure. Tto achieve this we have to process some steps in the following way: Let us assume TableName = 'Employee' and ColumnName = 'EmployeeId' 1. Add new column 'EmployeeId_new' in the 'Employee' table ALTER TABLE Employee ADD EmployeeId_new INT IDENTITY(1,1)

Now remove column 'EmployeeId' from 'Employee' table ALTER TABLE Employee DROP COLUMN EmployeeId This will throw error because of Primary Key Constraint rules are applicable and validating column structure. *### 'Msg 5074, Level 16, State 1, Line 1 The object [PK_dbo.Employee] is dependent on colmn [EmployeeId].'### So we have to remove the Primary Key constraint first from the table 'Employee' then we can remove the column ALTER TABLE Employee DROP constraint [PK_dbo.Employee] Now we can remove the column 'EmployeeId' from 'Employee' table as did in the previous step where we got error ALTER TABLE Employee DROP COLUMN EmployeeId Now Column 'EmployeeId' removed from table So we will Rename the newly added new column 'EmployeeId_new' with 'EmployeeId' sp_rename 'Employee.EmployeeId', 'EmployeeId_new', 'COLUMN' To rearrange the table in the same form as It was, we have to add Primary Key Constraint for the column 'EmployeeId' ALTER TABLE Employee add constraint [PK_dbo.Employee] primary key (EmployeeId)

8. 现在，带有'EmployeeId'的表'Employee'随着现有的主键约束被修改为Identity规则

As I understood in normal cases we are creating a table with Primary key which is having Identity property So Rename or Delete a column which is associated with Primary Key constraint will not be possible because constraint Rules are validating column structure. Tto achieve this we have to process some steps in the following way: Let us assume TableName = 'Employee' and ColumnName = 'EmployeeId' 1. Add new column 'EmployeeId_new' in the 'Employee' table ALTER TABLE Employee ADD EmployeeId_new INT IDENTITY(1,1)

Now remove column 'EmployeeId' from 'Employee' table ALTER TABLE Employee DROP COLUMN EmployeeId This will throw error because of Primary Key Constraint rules are applicable and validating column structure. *### 'Msg 5074, Level 16, State 1, Line 1 The object [PK_dbo.Employee] is dependent on colmn [EmployeeId].'### So we have to remove the Primary Key constraint first from the table 'Employee' then we can remove the column ALTER TABLE Employee DROP constraint [PK_dbo.Employee] Now we can remove the column 'EmployeeId' from 'Employee' table as did in the previous step where we got error ALTER TABLE Employee DROP COLUMN EmployeeId Now Column 'EmployeeId' removed from table So we will Rename the newly added new column 'EmployeeId_new' with 'EmployeeId' sp_rename 'Employee.EmployeeId', 'EmployeeId_new', 'COLUMN' To rearrange the table in the same form as It was, we have to add Primary Key Constraint for the column 'EmployeeId' ALTER TABLE Employee add constraint [PK_dbo.Employee] primary key (EmployeeId)

8. 现在，带有'EmployeeId'的表'Employee'随着现有的主键约束被修改为Identity规则

考虑使用SEQUENCE而不是IDENTITY。

在sql server 2014(我不知道低版本)，你可以简单地使用序列。

CREATE SEQUENCE  sequence_name START WITH here_higher_number_than_max_existed_value_in_column INCREMENT BY 1;

ALTER TABLE table_name ADD CONSTRAINT constraint_name DEFAULT NEXT VALUE FOR sequence_name FOR column_name

从这里开始:将序列作为列的默认值

这里有一个很酷的解决方案: 在列上添加或删除标识属性

简而言之，在SQL管理器中手动编辑您的表，切换标识，不要保存更改，只显示将为更改创建的脚本，复制它并稍后使用。

这节省了大量的时间，因为它(脚本)包含了所有与您更改的表相关的外键、索引等。手动写这个…上帝保佑。

您不能更改现有列的标识。

你有两个选择，

创建一个带有标识的新表并删除现有表 创建一个具有标识的新列并删除现有列

方法1。(新表)在这里，您可以保留新创建的标识列上的现有数据值。请注意，如果不满足'if not exists'，您将丢失所有数据，因此请确保您将条件也放在drop上!

CREATE TABLE dbo.Tmp_Names
    (
      Id int NOT NULL
             IDENTITY(1, 1),
      Name varchar(50) NULL
    )
ON  [PRIMARY]
go

SET IDENTITY_INSERT dbo.Tmp_Names ON
go

IF EXISTS ( SELECT  *
            FROM    dbo.Names ) 
    INSERT  INTO dbo.Tmp_Names ( Id, Name )
            SELECT  Id,
                    Name
            FROM    dbo.Names TABLOCKX
go

SET IDENTITY_INSERT dbo.Tmp_Names OFF
go

DROP TABLE dbo.Names
go

Exec sp_rename 'Tmp_Names', 'Names'

方法2(新列)不能在新创建的标识列上保留现有数据值，标识列将保留数字序列。

Alter Table Names
Add Id_new Int Identity(1, 1)
Go

Alter Table Names Drop Column ID
Go

Exec sp_rename 'Names.Id_new', 'ID', 'Column'

请参阅以下Microsoft SQL Server论坛帖子了解更多细节:

如何将列更改为identity(1,1)

您不能这样做，您需要添加另一列，删除原来的列并重命名新列，或者创建一个新表，复制数据并删除旧表，然后将新表重命名为旧表

如果你使用SSMS并在设计器中将标识属性设置为ON，下面就是SQL Server在幕后所做的事情。因此，如果你有一个名为[user]的表，如果你设置UserID和identity，就会发生这样的情况

BEGIN TRANSACTION
SET QUOTED_IDENTIFIER ON
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE
SET ARITHABORT ON
SET NUMERIC_ROUNDABORT OFF
SET CONCAT_NULL_YIELDS_NULL ON
SET ANSI_NULLS ON
SET ANSI_PADDING ON
SET ANSI_WARNINGS ON
COMMIT
BEGIN TRANSACTION

GO

GO
CREATE TABLE dbo.Tmp_User
    (
    UserID int NOT NULL IDENTITY (1, 1),
    LastName varchar(50) NOT NULL,
    FirstName varchar(50) NOT NULL,
    MiddleInitial char(1) NULL

    )  ON [PRIMARY]
GO

SET IDENTITY_INSERT dbo.Tmp_User ON
GO
IF EXISTS(SELECT * FROM dbo.[User])
 EXEC('INSERT INTO dbo.Tmp_User (UserID, LastName, FirstName, MiddleInitial)
    SELECT UserID, LastName, FirstName, MiddleInitialFROM dbo.[User] TABLOCKX')
GO
SET IDENTITY_INSERT dbo.Tmp_User OFF
GO

GO
DROP TABLE dbo.[User]
GO
EXECUTE sp_rename N'dbo.Tmp_User', N'User', 'OBJECT'
GO
ALTER TABLE dbo.[User] ADD CONSTRAINT
    PK_User PRIMARY KEY CLUSTERED 
    (
    UserID
    ) ON [PRIMARY]

GO
COMMIT

已经说过，有一种方法可以通过设置位值来破解系统表，但这是不支持的，我不会这么做