Can a sql server table have two identity columns?

Question

I need to have one column as the primary key and another to auto increment an order number field. Is this possible?

EDIT: I think I\'ll just use a composite number a

Answer 1

You can use Sequence for second column with default value IF you use SQL Server 2012

--Create the Test schema
CREATE SCHEMA Test ;
GO

-- Create a sequence
CREATE SEQUENCE Test.SORT_ID_seq
    START WITH 1
    INCREMENT BY 1 ;
GO

-- Create a table
CREATE TABLE Test.Foo
    (PK_ID int IDENTITY (1,1) PRIMARY KEY,
    SORT_ID int not null  DEFAULT (NEXT VALUE FOR Test.SORT_ID_seq));
GO

INSERT INTO Test.Foo VALUES ( DEFAULT )
INSERT INTO Test.Foo VALUES ( DEFAULT )
INSERT INTO Test.Foo VALUES ( DEFAULT )

SELECT * FROM Test.Foo 

-- Cleanup
--DROP TABLE Test.Foo
--DROP SEQUENCE Test.SORT_ID_seq
--DROP SCHEMA Test

http://technet.microsoft.com/en-us/library/ff878058.aspx

Answer 2

create table #tblStudent
(
    ID int primary key identity(1,1),
    Number UNIQUEIDENTIFIER DEFAULT NEWID(),
    Name nvarchar(50)
)

Two identity column is not possible but if you accept to use a unique identifier column then this code does the same job as well. And also you need an extra column - Name column- for inserting values.

Example usage:

insert into #tblStudent(Name) values('Ali')

select * from #tblStudent

---

Ps: NewID() function creates a unique value of type uniqueidentifier.

Answer 3

No it is not possible to have more than one identity column.

The Enterprise Manager does not even allow you to set > 1 column as identity. When a second column is made identity

Also note that @@identity returns the last identity value for the open connection which would be meaningless if more than one identity column was possible for a table.