Oracle 三种常与开窗组合使用的方法

最新推荐文章于 2024-05-12 10:22:15 发布

Coup_de_foudre

最新推荐文章于 2024-05-12 10:22:15 发布

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分类专栏： oracle 文章标签：开窗 Oracle

本文链接：https://blog.youkuaiyun.com/wolf_prince/article/details/92765367

开窗函数是日常工作中经常用到的sql语法，顾名思义，开窗函数的作用就是打开一扇窗户，打破传统的分组和查询方式，对数据进行操作，具体可以上网查询了解，这里介绍三种较为常用的三种与其他方法组合使用的用法

1.avg 如果样本数据具有多个类，我们需要将每个类的平均值坐位样本的一个指标，那莫我们就需要用到开窗函数和avg()组合使用

例如：计算本班的平均成绩（添加一列平均成绩与原成绩作对比）

select 
id,
name,
nj,
class,
score,
avg(score)over(partition by nj,class) as avg_score
from student

2.sum 如果我们需要添加一个指标，此指标是对以往数据的汇总，即只统计之前的数据，而不是简单的对某一指标汇总这里就需要开窗函数与sum函数组合使用
例如对当前时间之前的花销统计：

select 
id,
insert_time,
money,
sum(money)over(partition by 1 order by id)  as sum_money
from lb_rc

3.row_number() 如果我们需要对某一类的某一个指标进行排序,那么就需要开窗函数与row_number()函数混合使用
例如：查询班内排名和级部排名

select 
id,
name,
nj,
class,
china,
math,
eng,
score,
row_number()over(partition by nj,class order by score desc) as class_ranking
row_number()over(partition by nj order by score desc) as grade_ranking
from student

附赠建表语句

create table lb_rc(
id           number,
insert_time  varchar2(32),
money        number
);

create table STUDENT
(
  id    NUMBER,
  name  VARCHAR2(64),
  nj    NUMBER,
  class NUMBER,
  china NUMBER,
  math  NUMBER,
  eng   NUMBER,
  score NUMBER
);

student表数据生成语句

# -*- coding: utf-8 -*-
"""
Created on Mon Jun 17 09:47:29 2019

@author: liangbin01
"""
import random
import cx_Oracle
import datetime

tns_name = cx_Oracle.makedsn('127.0.0.1', '1521', 'orcl')
con = cx_Oracle.connect('C##Apple', 'wolf', tns_name, encoding='utf-8')
cur = con.cursor() 
###509个常用姓氏
xing_shi = ["赵","钱","孙","李","周","吴","郑","王","冯","陈","褚","卫","蒋","沈","韩","杨","朱","秦","尤","许",
            "何","吕","施","张","孔","曹","严","华","金","魏","陶","姜","戚","谢","邹","喻","柏","水","窦","章",
            "云","苏","潘","葛","奚","范","彭","郎","鲁","韦","昌","马","苗","凤","花","方","俞","任","袁","柳",
            "酆","鲍","史","唐","费","廉","岑","薛","雷","贺","倪","汤","滕","殷","罗","毕","郝","邬","安","常",
            "乐","于","时","傅","皮","卞","齐","康","伍","余","元","卜","顾","孟","平","黄","和","穆","萧","尹",
            "姚","邵","湛","汪","祁","毛","禹","狄","米","贝","明","臧","计","伏","成"