Oracle SQL:: 子查询中带有 orderby 的 Rownum 抛出缺少括号

Posted 2023-05-09

【中文标题】Oracle SQL:: 子查询中带有 orderby 的 Rownum 抛出缺少括号

【英文标题】：Oracle SQL:: Rownum with orderby in a subquery throws missing parenthesis

【发布时间】：2019-02-20 01:27:49

【问题描述】：

我的 sql 如下所示。它为具有 orderby 子句的行抛出缺少括号。如何重写此查询以克服此错误？

update MY_TABLE1 a
    set (my_addr)=
    (select my_addr
        from MY_TABLE1 b
        where b.code1=a.code1
        and b.code2=a.code2
        and b.my_addr is not null
        and rownum = 1
        order by LAST_UPDTD_TMSTMP DESC)
    where a.my_addr is null
    and exists (select 1
        from MY_TABLE1 b
        where b.code1=a.code1
        and b.code2=a.code2
        and b.my_addr is not null)

如果我尝试再创建一个嵌套子查询，对别名“a”的引用就会消失。

update MY_TABLE1 a
    set (my_addr)=
    (select my_addr from (select my_addr
        from MY_TABLE1 b
        where b.code1=a.code1
        and b.code2=a.code2
        and b.my_addr is not null
        order by LAST_UPDTD_TMSTMP DESC) where rownum = 1)
    where a.my_addr is null
    and exists (select 1
        from MY_TABLE1 b
        where b.code1=a.code1
        and b.code2=a.code2
        and b.my_addr is not null)

非常感谢任何指针。

【问题讨论】：

如果您能提供示例数据，那将很有帮助

【参考方案1】：

您可以使用keep 来获取您想要的值：

update MY_TABLE1 a
    set my_addr = (select max(my_addr) keep (dense_rank first order by LAST_UPDTD_TMSTMP DESC)
                   from MY_TABLE1 b
                   where b.code1 = a.code1 and
                         b.code2 = a.code2 and
                         b.my_addr is not null
                  )
    where a.my_addr is null and
          exists (select 1
                  from MY_TABLE1 b
                  where b.code1 = a.code1 and
                        b.code2 = a.code2 and
                        b.my_addr is not null
                 );

【讨论】：

感谢您的解决方案。这有效！非常感谢。