oracle/mysql数据库多条重复数据如何取最新的

目录

• MYSQL
• 1、分组取最新的，再用最新的字段连表，回查数据
• ①按分组字段取最新的，通过主键id回表查数据
• ②非主键字段
• ORACLE
• 1、原理讲解-可直接看2
• 2、在重复数据取最新的
• 3、若要删除不满足条件
• 附：ORACLE 查询某个时间之前的重复数据中时间最早的一条记录
• 总结 

select * from table_name
WHERE id in (
select max(id) id from table_name GROUP BY 分组字段)

SELECT r.*
FROM records r
INNER JOIN (
    SELECT group_id, MAX(timestamp) as latest
    FROM records
    GROUP BY group_id
) as latest_records 
ON r.group_id = latest_records.group_id 
AND r.timestamp = latest_records.latest;

SELECT *  
FROM (  
    SELECT t.*,  
           ROW_NUMBER() OVER (PARTITION BY LOCALAUTHID ORDER BY LASTUPDATETIME DESC) AS rn  
    FROM USER_LOCALAUTH_STATE t  
) t  
WHERE t.rn = 1;

SELECT *  
FROM (  
    SELECT t.*,ROW_NUMBER() OVER (PARTITION BY LOCALAUTHID ORDER BY LASTUPDATETIME DESC) AS rn  
    FROM    
        (
            -- 筛选存在重复的数据，count(LOCALAUTHID) > 1
            select * from USER_LOCALAUTH_STATE
            where LOCALAUTHID   in (
                SELECT LOCALAUTHID
                FROM USER_LOCALAUTH_STATE WHERE STATE = 1 AND BUSINESSTYPE=1
                group by LOCALAUTHID having count(LOCALAUTHID) > 1)
        ) t
    ) rt  
WHERE rt.rn = 1;

select * from (select row_number() over (partition by certno order by consigndate) rn, a.* from US_ADDCONSIGN a where 1=1 and state=1 ) where rn=1 and to_date(consigndate,'yyyymmdd')<to_date('20210101','yyyymmdd');