Question

这是我试图回答的问题：

我拥有的是：

SELECT DISTINCT a1.acnum
FROM academic a1, academic a2
WHERE a1.deptnum = a2.deptnum
AND a1.acnum <> a2.acnum
AND a1.acnum IN (Select acnum
from interest
group by acnum
having count(acnum) >1);

这是错误的，因为我正在做的事情如果acnum（学号）218与acnum 217在同一部门工作，AND与acnum 199（diff部门）具有相同的兴趣，那么我将acnum 218添加到列表中。

但是，我只应该添加第218和217页，如果他们两个都有相同数量的野外兴趣。

  兴趣表有fieldnum，acnum

学术表有acnum，deptnum，name

department table有deptnum，deptName

 FIELDNUM           ACNUM DESCRIP                                                                        
------------------ -------------------- 
292                 100  Multiprocessor and Special purpose computer design                               
293                 100  General (HW)                                                                     
293                 197  Computer architecture

输出应该只列出所有学者的号码.. 但要明确一点：

Acnum Deptnum Interest
1        1       g&f
2        1       g&f
3        2        f
4        3        l
5        4       r&l
6        4       r&l

输出应为： 1 2 五 6

Answer 1

未经测试但应该是好的

SELECT DISTINCT a1.acnum
FROM academic a1
INNER JOIN academic a2 ON a1.deptnum = a2.deptnum
                          AND 
                          a1.acnum <> a2.acnum
INNER JOIN interest i1 ON a1.acnum=i1.acnum
GROUP BY a1.acnum
HAVING COUNT(i1.acnum)=(SELECT COUNT(*)
                        FROM interest i2
                        WHERE i1.acnum=i2.acnum)

Answer 2

也许使用JOIN可以在这里给你更好的结果：

SELECT DISTINCT a1.acnum
FROM academic a1
JOIN academic a2
ON a1.deptnum = a2.deptnum
AND a1.acnum <> a2.acnum
AND a1.acnum IN (Select acnum
from interest
group by acnum
having count(acnum) >1);

Answer 3

根据我的理解，它应该有效

SELECT 
      listagg(a1.acnum,',') within group( order by a1.acnum) , a1.deptnum,a2.cnt
FROM 
     academic a1,
     (Select 
            acnum,count(*) as cnt
      from interest
      group by acnum
     ) a2
where 
     a1.acnum=a2.acnum
group by 
     a1.deptnum,a2.cnt
having count(*)>1;

Answer 4

使用公用表表达式（子查询）来获取学者，他们的部门以及他们的interestes计数。然后从中查询两次以获得所需的输出。

with cte as ( select a.acnum
                     , a.deptnum
                     , count(i.acnum) as int_cnt
              from academic a
                   , interest i
              where i.acnum = a.acnum
              group by  a.acnum
                     , a.deptnum
            )
select ct1.acnum
       , cte1.deptnum
       , cte1.in_cnt
from cte cte1
     , cte cte2
where cte2.deptnum = cte1.deptnum 
and cte2.int_cnt = cte1.int_cnt  
and cte2.acnum != cte1.acnum 
order by cte1.deptnum
         , cte1.acnum

警告 - 没有经过实际测试，所以虽然逻辑是合理的，但语法可能会出错;）

使用子查询进行比较

4 个答案: