Question

如果我有下表，我需要删除所有早于（现在 - x天）但不在最近n个记录中的记录。

具体示例：用户无法在90天内重复使用密码和可能无法重复使用最近10个密码。如果我每隔90天更改一次密码，我仍然无法重复使用密码进行10次更改。

CREATE TABLE PASSWORD_HISTORY (
            ID BIGINT NOT NULL AUTO_INCREMENT,
            USER_NAME VARCHAR(255) NOT NULL,
            PASSWORD VARCHAR(255) NOT NULL,
            SALT VARCHAR(255),
            CREATED_TIMESTAMP BIGINT NOT NULL,
            UPDATED_TIMESTAMP BIGINT NOT NULL,
            TENANT_ID INTEGER DEFAULT -1234,
            PRIMARY KEY (ID)
)ENGINE INNODB;

Answer 1

-- drop table password_history;
create table password_history
(
id bigint null auto_increment primary key,
user_name varchar(255) not null,
created_timestamp bigint not null
);

-- delete from password_history where id>0; -- safe mode sometimes barfs
insert password_history (user_name,created_timestamp) values ('fred',100);
insert password_history (user_name,created_timestamp) values ('fred',200);
insert password_history (user_name,created_timestamp) values ('fred',300);
insert password_history (user_name,created_timestamp) values ('fred',400);
insert password_history (user_name,created_timestamp) values ('fred',401);
insert password_history (user_name,created_timestamp) values ('fred',402);
insert password_history (user_name,created_timestamp) values ('fred',403);
insert password_history (user_name,created_timestamp) values ('fred',404);
insert password_history (user_name,created_timestamp) values ('fred',405);
insert password_history (user_name,created_timestamp) values ('fred',406);
insert password_history (user_name,created_timestamp) values ('fred',407);
insert password_history (user_name,created_timestamp) values ('fred',500);
insert password_history (user_name,created_timestamp) values ('fred',555);

insert password_history (user_name,created_timestamp) values ('fred',unix_timestamp(now()) );
insert password_history (user_name,created_timestamp) values ('stan',unix_timestamp(now()) );

alter table password_history add deleteMe int;

select * from password_history;

-- variables n and d
-- n=10, users last 10 records
-- d=90, last 90 days
-- rows where password created more than 90 days ago (replace 90 below as desired)
select * from password_history 
where unix_timestamp(now()) - created_timestamp>(60*60*24*90)
order by id desc

-- update password_history set deleteMe=1 where id>0;  -- safe mode sometimes barfs

-- update password_history set deleteMe=null where id>0; -- safe mode sometimes barfs

update password_history
join 
(
select ph.id,ph.user_name,ph.created_timestamp
from password_history ph
join
(
select ph.id,ph.user_name,ph.created_timestamp 
from password_history ph
join
(
select user_name,max(id),max(created_timestamp),count(*) as theCount
from password_history xx
group by user_name
having theCount>10
) inR2
on ph.user_name=inR2.user_name
order by ph.user_name,ph.created_timestamp desc
limit 10
) inR1
on ph.id=inR1.id
) bigThing
on password_history.id=bigThing.id
set deleteMe='1'
where password_history.id>0 -- this gets rid of the safe mode barfing

update password_history
join 
(
select user_name from password_history p2 where p2.deleteMe=1
) phMany
on password_history.user_name=phMany.user_name
set deleteMe=2
where password_history.deleteMe is null

-- select * from password_history order by user_name,created_timestamp desc;

-- look at the ones with deleteMe=2

Answer 2

DELETE 
FROM PASSWORD_HISTORY
Where PASSWORD_HISTORY.ID Not IN

(
    SELECT ID FROM(SELECT pass1.[USER_NAME], Count(*) num, pass1.ID
    FROM Password_History pass1 JOIN Password_History pass2
        ON pass1.[USER_NAME] = pass2.[USER_NAME] AND pass1.ID <= pass2.ID
    Group BY pass1.[USER_NAME], pass1.ID
    Having Count(*) <=  10

) a 

)
AND CREATED_TIMESTAMP <= Convert(int, DATEADD(day, -90, GetDate()))

如果这些行属于具有10个以上记录的用户名，并且这些行的Created_TimeStamp超过90天，则只会删除ID最低的行。当然，您应该使用SELECT *代替DELETE来运行此操作，以确保它能够为您提供所需内容。另外，我会使用Begin Transaction;运行并准备好Rollback Transaction;，如果它在删除时出现问题。

Answer 3

如果我理解正确，您希望删除最近记录超过90天且密码不在最近90天内的记录。我不确定你为什么要删除它们。您可以在查询数据时强制执行这些规则，而不是在数据本身中。然后，如果您愿意，可以轻松地将规则更改为120天。

在任何情况下，如果只为每个用户枚举密码，这将更加简单。但它们不是，MySQL不支持row_number()。这表明使用变量来枚举结果。由于MySQL的规则，这需要子查询和join中的delete。其余的只是基本的条件逻辑：

delete ph
    from password_history ph join
         (select ph2.*,
                 (@rn := if(@u = user_name, @rn + 1,
                            if(@u := user_name, 1, 1)
                           )
                 ) as seqnum
          from password_history ph2 cross join
               (select @rn := 0, @u := '') params
          order by user_name, created_timestamp desc
         ) ph2
         on ph2.id = ph.id
    where ph2.seqnum > 10 and
          ph.created_timestamp <= date_sub(curdate(), interval 90 day)

SQL删除时间戳早于（现在 - x天）的所有行，但保留最近的n条记录

3 个答案: