c# - How to set Identity Specification YES in 2 columns in a table in SQL Server 2008 -

how set identity specification yes in 2 columns in table in sql server 2008 ?

example:

id int,  catid int, 

for "@id" using primary key , set identity yes. allow not null.

for "@catid" want set identity yes also,

but when set identity yes "@catid" column, "@id" column becomes identity no itself.

i want @catid generate id @id.

check picture attached plz. , suggest me

it seems having table design issues. why have 2 identity columns? stated in comments, values either same or computable original identity specification:

create table mytable (     id int identity(1,1) not null primary key,     catid id, -- computed column     myfield nvarchar(100) null ) 

yields:

id  catid   myfield 1   1       2   2       b 3   3       c 4   4       d 5   5       e 

now if have different value catid:

create table mytable (     id int identity(1,1) not null primary key,     catid id * 3, -- different value     myfield nvarchar(100) null ) 

we get:

id  catid   myfield 1   3       2   6       b 3   9       c 4   12      d 5   15      e 

either way never makes sense have multiple identity columns.