SQL优化之over的使用

select t.grade, t.losal from salgrade t

select t1.grade, t1.losal, sum(t2.losal)
  from salgrade t1
  join salgrade t2
    on t2.grade <= t1.grade
 group by t1.grade, t1.losal
 order by 1, 2

select grade, losal, sum(losal) over(order by grade) from salgrade

打开oracle执行计划简单示例
或

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