达梦数据库之 PERCENT_RANK()over()函数和 PERCENTILE_CONT() WITHIN GROUP()OVER()函数详解

排列百分比 PERCENT_RANK

例 求图书的现价排列百分比。

SELECT NAME, PERCENT_RANK() OVER(ORDER BY NOWPRICE) AS NTILE FROM 
PRODUCTION.PRODUCT; 

查询结果如下：

NAME	NTILE
老人与海	0.000000000000000E+000
突破英文基础词汇	1.111111111111111E-001
工作中无小事	2.222222222222222E-001
水浒传	3.333333333333333E-001
红楼梦	4.444444444444444E-001

连续百分比 PERCENTILE_CONT 和分布百分比 PERCENTILE_DISC 分析函数。
PERCENTILE_CONT函数也是Oracle中用于计算分位数的窗口函数之一。与PERCENTILE_DISC函数不同的是，PERCENTILE_CONT函数会返回一个连续值，而不是精确匹配给定百分位的数据值。

<PERCENTILE_CONT|PERCENTILE_DISC> (< 参 数 >) WITHIN GROUP(<ORDER BY 项 >) OVER 
([<PARTITION BY 项>])

SELECT NAME, PERCENTILE_CONT(0.5) WITHIN GROUP(ORDER BY NOWPRICE) OVER() AS 
PERCENTILE_CONT FROM PRODUCTION.PRODUCT; 

查询结果如下：

NAME	PERCENTILE_CONT
老人与海	17.6
突破英文基础词汇	17.6
工作中无小事	17.6
水浒传	17.6
红楼梦	17.6
鲁迅文集(小说、散文、杂文)全两册	17.6

使用方法

创建一个临时表

create table EMP
(
  EMPNO    NUMBER(4) not null,
  ENAME    VARCHAR2(10),
  JOB      VARCHAR2(9),
  MGR      NUMBER(4),
  HIREDATE DATE,
  SAL      NUMBER(7,2),
  COMM     NUMBER(7,2),
  DEPTNO   NUMBER(2)
);

插入数据

insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7369, 'SMITH', 'CLERK', 7902, to_date('17-12-1980', 'dd-mm-yyyy'), 800.00, null, 20);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7499, 'ALLEN', 'SALESMAN', 7698, to_date('20-02-1981', 'dd-mm-yyyy'), 1600.00, 300.00, 30);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7521, 'WARD', 'SALESMAN', 7698, to_date('22-02-1981', 'dd-mm-yyyy'), 1250.00, 500.00, 30);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7566, 'JONES', 'MANAGER', 7839, to_date('02-04-1981', 'dd-mm-yyyy'), 2975.00, null, 20);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7654, 'MARTIN', 'SALESMAN', 7698, to_date('28-09-1981', 'dd-mm-yyyy'), 1250.00, 1400.00, 30);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7698, 'BLAKE', 'MANAGER', 7839, to_date('01-05-1981', 'dd-mm-yyyy'), 2850.00, null, 30);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7782, 'CLARK', 'MANAGER', 7839, to_date('09-06-1981', 'dd-mm-yyyy'), 2450.00, null, 10);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7788, 'SCOTT', 'ANALYST', 7566, to_date('19-04-1987', 'dd-mm-yyyy'), 3000.00, null, 20);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7839, 'KING', 'PRESIDENT', null, to_date('17-11-1981', 'dd-mm-yyyy'), 5000.00, null, 10);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7844, 'TURNER', 'SALESMAN', 7698, to_date('08-09-1981', 'dd-mm-yyyy'), 1500.00, 0.00, 30);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7876, 'ADAMS', 'CLERK', 7788, to_date('23-05-1987', 'dd-mm-yyyy'), 1100.00, null, 20);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7900, 'JAMES', 'CLERK', 7698, to_date('03-12-1981', 'dd-mm-yyyy'), 950.00, null, 30);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7902, 'FORD', 'ANALYST', 7566, to_date('03-12-1981', 'dd-mm-yyyy'), 3000.00, null, 20);
insert into emp (EMPNO, ENAME, JOB, MGR, HIREDATE, SAL, COMM, DEPTNO)
values (7934, 'MILLER', 'CLERK', 7782, to_date('23-01-1982', 'dd-mm-yyyy'), 1300.00, null, 10);
commit;

查询表：

select *  from emp e; 

按薪水的倒序，取薪水的排名，及一定百分比的薪水值

select e.ename,e.sal,e.deptno,
       percent_rank() over(partition by deptno order by sal desc) p_rank, --以deptno分组，以sal倒序，取出百分比排名
       PERCENTILE_CONT(0) within group(order by sal desc)
        over(partition by deptno) max_sal ,                               --以deptno分组，以sal倒序，取出占0%的薪水
       PERCENTILE_CONT(0.25) within group(order by sal desc)
        over(partition by deptno) max_sal_25,                             --以deptno分组，以sal倒序，取出25%的薪水
       PERCENTILE_CONT(0.5) within group(order by sal desc)
        over(partition by deptno) max_sal_50,                             --以deptno分组，以sal倒序，取出50%的薪水
       PERCENTILE_CONT(0.75) within group(order by sal desc)              --以deptno分组，以sal倒序，取出70%的薪水
        over(partition by deptno) max_sal_75                             
   from emp e;