sql的两道面试题，请大家帮忙！

1 select a,b into #temp from T

  delete from T

  insert into T(a,b)select (b,a) from #temp

--第二题

declare @tb table(id int)

insert @tb

select 1 union all

select 2 union all

select 3 union all

select 4 union all

--5是断号

select 6 union all

select 7 union all

select 8 union all

select 9 union all

select 10



select max(a.id - 1)

from @tb a

left join @tb b on a.id = b.id + 1

where b.id is null

SELECT id+1 FROM test a WHERE NOT EXISTS (SELECT 1 FROM test WHERE id=a.id+1) AND id<>(select max(id) FROM test)

SELECT B AS A,A AS B FROM T



--如果是更新物理表



UPDATE T SET A=B,B=A

SELECT B AS A,A AS B FROM T



DECLARE @ID INT 

SET @ID=(SELECT TOP 1 ID FROM T ORDER BY NEWID())

DELETE T WHERE ID=@ID



被删除的就是@ID