Adding Identity

how can i change a column attribute using alter table in sql server 2005. i want to add an identity property to my column userid , which deosn't have an identity property defined when created.

i tried this.

alter table userlookup alter column userid int identity(1,1) not null

i got this error:

Incorrect syntax near the keyword 'identity'.

As far as I know (I might be wrong), you can't do that if you already have some values in that column.

Anyway, if you particular table's requirements permit this (stuff like foreign keys pointing to it, etc.), you can just drop it and re-create it anew, this time as an identity column.

|||Open management studio
go to the table you need to alter
open the Modify context menu
edit changes
now right click and use the last menu item: Generate script for changes

You can use this way to know scripting template for any change you need.

In that case you will see that SSMS will create a temp table, performs a bulk insert, drops the original table and then renames the temp table to the original name.
something like this:

BEGIN TRANSACTION
SET QUOTED_IDENTIFIER ON
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
CREATE TABLE dbo.Tmp_TRACE01
(
RowNumber int NOT NULL,
EventClass int NULL,
TextData ntext NULL,
NTUserName nvarchar(128) NULL,
ClientProcessID int NULL,
ApplicationName nvarchar(128) NULL,
LoginName nvarchar(128) NULL,
SPID int NULL,
Duration bigint NOT NULL IDENTITY (1, 1),
StartTime datetime NULL,
Reads bigint NULL,
Writes bigint NULL,
CPU int NULL
) ON [PRIMARY]
TEXTIMAGE_ON [PRIMARY]
GO
DECLARE @.v sql_variant
SET @.v = cast(N'760' as int)
EXECUTE sp_addextendedproperty N'Build', @.v, N'SCHEMA', N'dbo', N'TABLE', N'Tmp_TRACE01', NULL, NULL
SET @.v = cast(N'8' as int)
EXECUTE sp_addextendedproperty N'MajorVer', @.v, N'SCHEMA', N'dbo', N'TABLE', N'Tmp_TRACE01', NULL, NULL
SET @.v = cast(N'0' as int)
EXECUTE sp_addextendedproperty N'MinorVer', @.v, N'SCHEMA', N'dbo', N'TABLE', N'Tmp_TRACE01', NULL, NULL
GO
SET IDENTITY_INSERT dbo.Tmp_TRACE01 ON
GO
IF EXISTS(SELECT * FROM dbo.TRACE01)
EXEC('INSERT INTO dbo.Tmp_TRACE01 (RowNumber, EventClass, TextData, NTUserName, ClientProcessID, ApplicationName, LoginName, SPID, Duration, StartTime, Reads, Writes, CPU)
SELECT RowNumber, EventClass, TextData, NTUserName, ClientProcessID, ApplicationName, LoginName, SPID, Duration, StartTime, Reads, Writes, CPU FROM dbo.TRACE01 WITH (HOLDLOCK TABLOCKX)')
GO
SET IDENTITY_INSERT dbo.Tmp_TRACE01 OFF
GO
DROP TABLE dbo.TRACE01
GO
EXECUTE sp_rename N'dbo.Tmp_TRACE01', N'TRACE01', 'OBJECT'
GO
ALTER TABLE dbo.TRACE01 ADD CONSTRAINT
PK__TRACE01__317735E1 PRIMARY KEY CLUSTERED
(
RowNumber
) WITH( STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]

GO
COMMIT