Use of Temp Table

create table t1(id int,name varchar(50))
insert into t1 values(1,'aaa')


select * from t1


drop table #temp

select * into #temp From t1
truncate table t1
alter table t1 drop column id
alter table t1 add id int identity(1,1)
insert into t1(name)
select NAME from #temp
select * from #temp

Suppose you have create table t1 by mistake id in int but now there are hundred of data and your requirement is to change in identity than this is the bast example of use temp table.