我想复杂了。。。
select no,sum((case when year=1999 then -1 else 1 end)*salary) from table
where year in(1999,2000)

group by no

having count(1)>1 and sum((case when year=1999 then -1 else 1 end)*salary)>8000

@QingchuanZhang 这个不错