Sql 查询需要很多时间

我有三张表，学生详细信息、学生分数和科目名称

受试者姓名

+----+------------------+
| ID |     Sub_Name     |
+----+------------------+
|  1 | Maths            |
|  2 | Physics          |
|  3 | Chemistry        |
|  4 | Biology          |
|  5 | Computer Science |
+----+------------------+

学生资料

+----+------------+-----------+-----+-------+--+
| ID | First_Name | Last_Name | Age | Class |  |
+----+------------+-----------+-----+-------+--+
|  1 | Rohit      | Sharma    |  28 |     3 |  |
|  2 | Shikhar    | Dhavan    |  27 |     2 |  |
|  3 | Virat      | Kohli     |  29 |     3 |  |
|  4 | MS         | Dhoni     |  30 |     2 |  |
|  5 | Hardik     | Pandya    |  25 |     3 |  |
+----+------------+-----------+-----+-------+--+

学生成绩

+----+------------+------------+---------------+
| ID | Student_Id | Subject_Id | Subject_Marks |
+----+------------+------------+---------------+
|  1 |          1 |          1 |            90 |
|  2 |          1 |          2 |            82 |
|  3 |          1 |          3 |            85 |
|  4 |          1 |          4 |            75 |
|  5 |          1 |          5 |            92 |
|  6 |          2 |          1 |            90 |
|  7 |          2 |          2 |            82 |
|  8 |          2 |          3 |            85 |
|  9 |          2 |          4 |            75 |
| 10 |          2 |          5 |            92 |
| 11 |          3 |          1 |            90 |
| 12 |          3 |          2 |            82 |
| 13 |          3 |          3 |            85 |
| 14 |          3 |          4 |            75 |
| 15 |          3 |          5 |            92 |
+----+------------+------------+---------------+

我使用这个查询来获取结果

select sd.First_Name
      ,sd.Last_Name
      ,sm.Subject_Id
      ,sm.Subject_Marks
from Student_Marks sm
    inner join Student_details sd
       on sm.Student_Id = sd.ID
where sm.Subject_Id in (select ID
                        from Subject_Name
                        where Sub_Name in ('Maths', 'Physics')
                       )
  and Student_Id in (select ID
                     from Student_details
                     where class in (2,3)
                    );

现在，这个查询花费了太多的时间来获取结果

如何优化此查询

---

编辑：

我使用hibernate获取结果，因此实际查询是：

select sd.First_Name
      ,sd.Last_Name
      ,sm.Subject_Id
      ,sm.Subject_Marks
from Student_Marks sm
    inner join Student_details sd
        on sm.Student_Id = sd.ID
where sm.Subject_Id in :SubName
  and Student_Id in (select ID
                     from Student_details
                     where class in :ClassIds
                    );

试试这个：

select sd.First_Name
      ,sd.Last_Name
      ,sm.Subject_Id
      ,sm.Subject_Marks
from Student_Marks sm
     inner join Student_details sd on sm.Student_Id = sd.ID
     inner join Subject_Name sn on sm.Subject_Id = sn.ID AND Sub_Name in ('Maths','Physics')
     inner join Student_details on Student_Id = Student_details.ID AND class in (2,3)

---

我不理解学生详细信息子查询。为什么说“给我你在查找2或3级的学生详细信息时找到的学生详细信息”而不是“给我2或3级的学生详细信息”

至于

subject\u name

：我加入表中，以便显示其名称。只选择ID并猜测哪个是数学，哪个是物理是没有意义的

您应该提供以下索引：

create index idx1 on subject_name(sub_name, id);
create index idx2 on student_details(class, id);
create index idx3 on student_marks(student_id, subject_id);
create index idx4 on student_marks(subject_id, student_id);

甚至包括指数：

create index idx1 on subject_name(sub_name, id, sub_name);
create index idx2 on student_details(class, id, first_name, last_name);
create index idx3 on student_marks(student_id, subject_id, subject_marks);
create index idx4 on student_marks(subject_id, student_id, subject_marks);

---

我不能说将使用索引idx3还是idx4。试试看，把没用的扔掉。（当然，DBMS可能决定根本不使用这些索引；它们只是一个报价。）

您是否做了

解释
来了解其中的关键点？实际上，有5万名学生的详细信息和1个CR.+行的学生分数。因此，查询需要3分钟以上的时间。我想减少这一时间@B001ᛦ这些表上有什么索引？您是否可以使用subject
ID
值而不是
Sub\u Name
？查询中的subject Name和class是来自java代码的列表。有没有办法从查询中删除此项。@iamdaveAre是否只传递主题名而不传递ID值？如果没有，您能否更改您的应用程序以执行此操作？
create index idx1 on subject_name(sub_name, id, sub_name);
create index idx2 on student_details(class, id, first_name, last_name);
create index idx3 on student_marks(student_id, subject_id, subject_marks);
create index idx4 on student_marks(subject_id, student_id, subject_marks);