How do I add the identity property to an existing column in SQL Server

Question

In SQL Server (in my case, 2005) how can I add the identity property to an existing table column using T-SQL?

Something like:

alter table tblFoo 
            


        

Answer 1

1. Create a New Table

   SELECT * INTO Table_New FROM Table_Current WHERE 1 = 0;
   

2. Drop Column from New Table

   Alter table Table_New drop column id;
   

3. Add column with identity

   Alter table Table_New add id int primary key identity; 
   

4. Get All Data in New Table

   SET IDENTITY_INSERT Table_New ON;
   INSERT INTO Table_New (id, Name,CreatedDate,Modified) 
   SELECT id, Name,CreatedDate,Modified FROM Table_Current;
   SET IDENTITY_INSERT Table_New OFF;
   

5. Drop old Table

   drop table Table_Current;
   

6. Rename New Table as old One

   EXEC sp_rename 'Table_New', 'Table_Current';