求一句 MySQL SQL 语句,表内指定字段重复的条目,以 UpdateTime 字段排序,只保留最新一条。。。 - V2EX
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uti6770werty
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求一句 MySQL SQL 语句,表内指定字段重复的条目,以 UpdateTime 字段排序,只保留最新一条。。。

  •  
  •   uti6770werty 2020-08-31 17:37:24 +08:00 2380 次点击
    这是一个创建于 1945 天前的主题,其中的信息可能已经有所发展或是发生改变。

    表名:rejectgoods 判断字段:name,size,city,address UpdateTime 是 datetime 类型
    表内所有条目,根据判断字段都相同的条目,如果存在>1 条,只保留 UpdateTime 最新的条目,其它删除。。。

    5 条回复    2020-09-01 09:32:45 +08:00
    kiracyan
        1
    kiracyan  
       2020-08-31 18:49:22 +08:00   1
    select rid from rejectgoods t1
    exists (select 1 from rejectgoods where t1. name = t2.name ..... and t1.address = t2. address and t1.updatetime < t2.updatetime )

    把查出来的 rid 删了
    LGA1150
        2
    LGA1150  
       2020-08-31 20:24:04 +08:00 via Android   1
    DELETE a
    FROM rejectgoods a, rejectgoods b
    WHERE a.name = b.name
    AND a.size = b.size
    AND ... (其他字段省略)
    ...
    AND a.UpdateTime < b.UpdateTime

    这样 UpdateTime 较小的就被删除
    uti6770werty
        3
    uti6770werty  
    OP
       2020-08-31 21:40:05 +08:00
    @kiracyan
    @LGA1150
    感谢两位,字段名称是英文的测试没问题,但是中文的字段名不行,
    尽管已经试过格式修改,因为不是很了解 MySQL,临急抱佛脚也不是很懂
    WHERE t1.`城市` = t2.`城市`
    WHERE a.城市 = b.城市的句式,


    1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE a.城市 = b.城市
    gavindexu
        4
    gavindexu  
       2020-09-01 05:57:54 +08:00 via iPhone
    给中文的字段名前后加上“`”就可以了啊
    muskill
        5
    muskill  
       2020-09-01 09:32:45 +08:00
    @LGA1150 直接 delete 不好吧
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