Question

我在oracle中有一个具有非唯一列值的表。这些组合也是非独特的。但是，特定顺序的关联必须是唯一的。我尝试了很多解决方案。 This 问题是最接近的，但我需要Oracle SQL中的解决方案。以下是我的表

--------------------------------------------------
  Teacher           subject             class_id
--------------------------------------------------
    Paul              English              001
    Paul              English              002
    Allen             English              003
    Sia               Maths                134
    John              Computer             913
    Jack              Physics              341
    Arlene            Maths                001
 -------------------------------------------------

查询应仅返回以下信息

English, Maths

即与多位教师相关的科目。

Answer 1

也许你想要这样的东西：

select listagg (subject, ', ') within group (order by subject) subjects
from (
    select subject from classes 
    group by subject
    having count(teacher)>1
);

SUBJECTS                                                                       
-------------------------
English, Maths

或者您可以使用分析函数获得相同的结果：

select listagg (subject, ', ') within group (order by subject) subjects
from (
    select subject,
    count(teacher) over (partition by subject) teachers,
    row_number() over (partition by subject order by class_id) rn 
    from classes
)
where teachers>1 and rn=1
;

Answer 2

如果我理解正确，您希望拥有多位教师的科目。这是一个带有having子句的简单聚合查询：

select subject
from t
group by subject
having min(teacher) <> max(teacher);

找出与Oracle中多个列值相关联的列值

2 个答案: