急求一解，关于加减的问题
table:score
字段   score     id
          77             1
          66             2
          55             3
          8１             4
score小于８０加５分   大于等于８０   减５分

------解决方案--------------------
select score = case when score <80 then score+5 else score-5 end, id from score
------解决方案--------------------
update score set score = case when score < 80 then score + 5 else score - 5 end
------解决方案--------------------
select score =(case when score <80 then score+5 else score-5 end), id from score
order by id