Error in modify table in sql

--create test table

create table table1 (col1 int, col2 varchar(30))

insert into table1 values (100, 'olddata')



 --add identity column

alter table table1 add col3 int identity(1,1)

GO



--rename or remove old column

exec sp_rename 'table1.col1', 'oldcol1', 'column'

OR

alter table table1 drop column col1

--rename new column to old column name

exec sp_rename 'table1.col3', 'col1', 'column'

GO



--add new test record and review table

insert into table1 values ( 'newdata')

select * from table1