SQL 中的两个条件必须为真

Question

我有两个table。

学生
学生兴趣

Table：学生

Id | Student Name
------------------
1  | John
2  | Alice

Table：学生兴趣

Id | SId | Interest
------------------
1  | 1   | Mathematics
2  | 1   | Science
1  | 2   | Environment
2  | 2   | English
2  | 2   | Mathematics

这两个table与“student Interest”中的外键相连Table

现在我想要对“数学”和“科学”都感兴趣的学生姓名

我试过了

Select s.Name from Student s
Inner Join StudentInterest si
ON
s.Id = si.SId
Where si.Interest IN ('Mathematics' , 'Science')

但它显示了两个学生，因为两个学生都对 'Mathematics' 感兴趣结果应该只有 1 个名为“John”的学生

Answer 1

如果你按学生分组，你可以select只有那些像这样有两种兴趣的人

Select s.Name 
from Student s
Inner Join StudentInterest si ON s.Id = si.SId
Where si.Interest IN ('Mathematics' , 'Science')
group by s.Name
having count(distinct si.Interest) = 2

或

Select s.Name 
from Student s
Inner Join StudentInterest si ON s.Id = si.SId
group by s.Name
having sum(case when si.Interest = 'Mathematics' then 1 else 0 end) > 0
   and sum(case when si.Interest = 'Science' then 1 else 0 end) > 0

SQL 中的两个条件必须为真

Two condition must be true in SQL

sql

relational-division