sql去除重复数据语句_sql中三种去重的方式

一、oracle去重1、创建测试数据create table test_duplicate_removal( c001 number, c002 varchar2(100));insert into test_duplicate_removal values(101, 'aa');insert into test_duplicate_removal values(102, 'aa');insert into test_duplicate_removal values(103, 'aa');insert into test_duplicate_removal values(104, 'bb');insert into test_duplicate_removal values(105, 'bb');insert into test_duplicate_removal values(106, 'cc');insert into test_duplicate_removal values(107, 'cc');insert into test_duplicate_removal values(108, 'dd');2、使用row_number() over()函数根据C002列去重创建一个rn列，根据C002进行分组，每个小组内再根据C001的值进行排序。

select c001,c002, row_number() over(partition by c002 order by c001 desc) rn from test_duplicate_removal通过rn筛选值为1的行，同时也就对C002进行了去重select * from (select c001,c002, row_number() over(partition by c002 order by c001 desc) rn from test_duplicate_removal) t where t.rn=1二、python的pandas模块去重方法1、将数据库数据导出保存为CSV2、pandas实现sql里排序函数row_number() over()功能import pandas as pd# 读取CSV数据df = pd.read_csv('test_duplicate_removal.csv')print('打印原始数据：')print(df)# 此处等价于sql里的排序函数row_number() over()功能df['RN'] = df['C001'].groupby(df['C002']).rank()print()print('根据C002分组，根据C001组内排序：')print(df)# 去重print()print('去重，筛选RN=1的行：')print(df[df['RN'] == 1])运行结果