oracle olap函数

/*sum()over()*/
--默认计算所有行的合计
select t.empno,t.ename,t.sal,t.deptno,sum(t.sal)over()
from scott.emp t;
--partition by分组合计
select t.empno,t.ename,t.sal,t.deptno,
       sum(t.sal)over(partition by t.deptno)
from scott.emp t
order by t.deptno,t.sal;
--partition by order by deptno分组累计
select t.empno,t.ename,t.sal,t.deptno,
       sum(t.sal)over(partition by t.deptno order by t.sal)
from scott.emp t;
--rows n preceding 取当前行+前n行=(n+1)行
--通过order by desc可以取后n行
select t.empno,t.ename,t.sal,t.deptno,
       sum(t.sal)over(order by t.deptno,t.sal rows 1 preceding)
from scott.emp t;
--rows 2n+1 取当前行+前n行+后n行=(2n+1)行
select t.empno,t.ename,t.sal,t.deptno,
       sum(t.sal)over(order by t.deptno,t.sal rows between 1 preceding and 1 following)
from scott.emp t;
/*first_value() over()*/
select deptno,ename,sal,hiredate,
　　first_value(ename) over(partition by deptno order by sal asc rows 5 preceding) first_ename
　　from emp  order by hiredate asc;
/*avg()over  count() over()  max()over() min()over()*/
select deptno,sal,
    sum(sal)over(partition by deptno) as sumsal,
　　avg(sal)over(partition by deptno) as avgsal,
　　count(*)over(partition by deptno) as count,
　　max(sal)over(partition by deptno) as maxsal
from emp;
/*rank()over() dese_rank()over() row_number()over()*/
select empno, deptno, sal,
    rank()   over (order by deptno desc nulls last) as rank,
    dense_rank()  over (partition by deptno order by sal desc nulls last) as dense_rank,
    row_number()  over(partition by deptno order by sal desc nulls last) as row_number
from emp;
/*stddev() over()*标准差/
select empno, deptno, sal,stddev(sal) over(order by sal)
from emp;