create table table1 (col1 int, col2 varchar(30))
insert into table1 values (100, 'olddata')
alter table table1 add col3 int identity(1,1)
GO
exec sp_rename 'table1.col1', 'oldcol1', 'column'
OR
alter table table1 drop column col1
exec sp_rename 'table1.col3', 'col1', 'column'
GO
insert into table1 values ( 'newdata')
select * from table1