需要查询更正

Question

select stdcode,name,degree_code,phone,startsemester,endsemester
from  (                   
         select distinct stdcode as stdcode,name as name,degree_code as degree_code,phone as phone,
              (
                SELECT sem_code
                FROM V_ALLSTUDATA b
                WHERE  a.name = b.name 
                and a.stdcode= b.stdcode 
                and a.degree_code=b.degree_code 
                and a.phone=b.phone
                AND  startsem=(select min(startsem) 
                               from V_ALLSTUDATA b)    
             ) as startsemester,
             (
                SELECT sem_code
                FROM V_ALLSTUDATA b
                WHERE  a.name = b.name 
                and a.stdcode= b.stdcode 
                and a.degree_code=b.degree_code 
                and a.phone=b.phone
                AND  startsem=(select 
                               max(startsem) from V_ALLSTUDATA a)
              ) as endsemester

                from V_ALLSTUDATA a
             );

我想 select sem_code 作为 startsem_code 和 sem_code 作为 lastsem_code

我该如何解决这个错误？

ORA-01427: single-row subquery returns more than one row
01427. 00000 - "single-row subquery returns more than one row"
*Cause:
*Action:

DATA ATTACHED HERE YOU CAN DOWNLOAD FOR YOU CONVENIENCE

Answer 1

因为子查询明确要求匹配min(startsem)或max(startsem)，我相信子查询只会return一个值。但是，它们可能 return 相同值的多个实例。

为了防止这种情况发生，我认为您需要将 distinct 添加到两个子查询中，如下所示：

            (select distinct sem_code
              from V_ALLSTUDATA b
               where  a.name = b.name and a.stdcode= b.stdcode and a.degree_code=b.degree_code and a.phone=b.phone
              and endsem=(select max(startsem) from V_ALLSTUDATA a)

            ) as endsemester

Answer 2

您在单个查询中有多个行，所以我认为您将使用 rownum。所以试试下面的查询

select stdcode,name,degree_code,phone,startsemester,endsemester
        from  (                   
                select distinct stdcode as stdcode,name as name,degree_code as degree_code,phone as phone,
              (
                SELECT sem_code
                      FROM V_ALLSTUDATA b
                      WHERE  a.name = b.name and a.stdcode= b.stdcode and a.degree_code=b.degree_code 
 and a.phone=b.phone
                     AND  startsem=(select min(startsem) from V_ALLSTUDATA b where rownum=1)

                    ) as startsemester,
                    (select sem_code
                      from V_ALLSTUDATA b
                       where  a.name = b.name and a.stdcode= b.stdcode and a.degree_code=b.degree_code and a.phone=b.phone
                      and endsem=(select max(startsem) from V_ALLSTUDATA a where rownum=1)

                    ) as endsemester

                from V_ALLSTUDATA a

             );

Answer 3

问题出在 return startsemester 和 endsemester 值的一个（或两个）SELECT 语句中。例如：

(SELECT sem_code
 FROM V_ALLSTUDATA b
 WHERE     a.name = b.name
   AND a.stdcode = b.stdcode
   AND a.degree_code = b.degree_code
   AND a.phone = b.phone
   AND startsem = (SELECT MIN (startsem)
                   FROM V_ALLSTUDATA b)) AS startsemester

不能return超过一个值。由于我们没有您的数据，因此无法回答 为什么 您有 too_many_rows。有几种解决方法，例如

使用聚合之一，例如MAX，例如select max(sem_code) from ...
看看 distinct 是否有帮助，例如select distinct sem_code from ...
将 rownum 包含在 where 子句中，例如... and rownum = 1

但是 - 从我的角度来看 - 你应该研究导致错误的原因并适当地修复它。也许您在 where 子句中遗漏了更多条件；谁知道？我们没有，你可能会。

Answer 4

     with tt AS
    ( select    f.stdcode,
             f.name,
             f.degree_code,
             f.phone,
             MIN(f.startsem)as startsemdate,
             MAX(f.startsem)as endsemedate
    FROM V_GRADUATED f
    GROUP BY 
      f.stdcode,
      f.name,
      f.degree_code,
      f.phone)
    select    tt.stdcode,
      tt.name,
      tt.degree_code,
      tt.phone,
      (select sem_code 
             from v_graduated a
            where a.stdcode=tt.stdcode 
             and a.startsem=tt.startsemdate) startsemester,
      (select sem_code
             from v_graduated a
             where a.stdcode=tt.stdcode 
            and a.startsem=tt.endsemedate) endsemester
      from tt

这就是我想要的......> 这是正确答案

enter image description here

需要查询更正

Query correction needed

sql

oracle

oracle10g