Question

ID  Semester  GPA   Center NAme   Date Check in
ID 1  Fall   3.0   A Center -    11/3/2000
ID 1  Fall   3.0   A Center -    11/4/2000
ID 1 Spring  3.5   B Center -    3/3/2000
ID 2 Fall    3.0   B Center -    11/5/2000
ID 3 Fall    3.0   C Center -    11/1/2000
ID 3 spring  3.2   C Center -    3/3/2000
ID 4 Fall    3.2   D Center -    11/10/2000
ID 4 Spring  3.0   D Center -    3/11/2000
.
.
.

...

寻找哪些辅导中心对学生更有效;哪个中心可以帮助学生增加学生的学习成绩。 GPA。

我想得到如下结果。

ID  -- Different GPA  -- Center
ID3  --     0.2       --C Center 
ID4  --    -0.4       --D Center 
.
.
.

所以我知道C中心比D中心更有效。

我在下面的每个ID中找到了春季和秋季学期之间不同GPA的代码。但是，我想按中心分组。

select DISTINCT(a.[Fake ID]), 
    b.GPA - a.GPA as diff
from tutor a
join tutor b on a.[Fake ID] = b.[Fake ID]
where a.Semester = 'Fall'
and b.Semester = 'Spring'
ORDER BY [Fake ID] DESC;

Answer 1

SELECT t.Id, t.Center, spring.Gpa - fall.Gpa
FROM tutor t
INNER JOIN tutor fall 
    ON t.ID = fall.ID AND fall.Semester='Fall' AND fall.Center = t.Center
INNER JOIN tutor spring 
    ON t.ID = spring.ID AND spring.Semester='Sprint' AND spring.Center = t.Center
        SELECT t.Id, t.Center, spring.Gpa - fall.Gpa
FROM tutor t
INNER JOIN tutor fall 
    ON t.ID = fall.ID AND fall.Semester='Fall' AND fall.Center = t.Center
INNER JOIN tutor spring 
    ON t.ID = spring.ID AND spring.Semester='Sprint' AND spring.Center = t.Center

从中心SQL的两个不同学期中找到不同的点

1 个答案: