填坑, join,left join 实现倒序,sql 默认排序的倒序 - V2EX
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heike8
V2EX    PostgreSQL

填坑, join,left join 实现倒序,sql 默认排序的倒序

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  •   heike8 2021-05-01 01:13:19 +08:00 2222 次点击
    这是一个创建于 1671 天前的主题,其中的信息可能已经有所发展或是发生改变。

    需求:

    https://i.imgur.com/s3xR8d1.png

    图片注释

    这是我自己个人的表,在实际中没有 id 字段,前人留下一万个关联查询 left join,inner join,、子查询 (不下四个 left join )

    找不出任何排序规则

    公司需求类似,把现有 left join 后的数据倒序

    order by 那么字段出来数据顺序都不对.

    解决:

    https://i.imgur.com/GC3hLzk.png

    图片注释

    row_number() over()

    添加自定义行号,再根据行号倒序。。o()o

    考虑分页(limit,OFFSET),行号是否会变化

    3 条回复    2021-05-01 16:29:15 +08:00
    rockddd
        1
    rockddd  
       2021-05-01 01:48:19 +08:00   2
    自从放了五一假期,我就再也看不懂任何字母了,好奇怪
    c6h6benzene
        2
    c6h6benzene  
       2021-05-01 12:18:41 +08:00 via iPhone
    over 里面还有 partition by 和 order by 可以写。
    heike8
        3
    heike8  
    OP
       2021-05-01 16:29:15 +08:00
    @c6h6benzene 是的,我测了下 写 order by 会增加耗时
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