--上機題1
--參加oop最近一次考試時間的最高分數和最低分數
select MAX(studentresult), MIN(studentresult) from Result
where ExamDate=
(
select MAX(ExamDate) from Result 
where SubjectId=
(
select SubjectId from Subject where SubjectName='oop'
)
)
and SubjectId=
(
select SubjectId from Subject where SubjectName='oop'
)


--上機題2

--使用in關鍵字的子查詢來查詢S1學期開設的課程


select SubjectName from Subject
where GradeId in
(
    select GradeId from Grade where GradeName='S1'
)


--上機題3

--查詢某課程最近一次考試缺考的學生名單 

select studentno, StudentName from Student 
where StudentNo not in
(
  select StudentNo from Result
  where SubjectId=
  (
  select SubjectId from Subject where SubjectName='oop'
  )
  and ExamDate=
(
select MAX(ExamDate) from Result 
where SubjectId=
(
select SubjectId from Subject where SubjectName='oop'
)
)
 
)
 and GradeId=
(
select GradeId from Subject where SubjectName='oop'
)

--上機題4
--檢查並更新S1的學生為S2


if exists(

select studentno,StudentName from Student 
where StudentNo in
(
  select StudentNo from Student where
  GradeId=
  (
  sleelct GradeId from grade where GradeName='S1'
  )
)
)
begin

update Student set GradeId=2
where GradeId in
(
  select GradeId from Grade where GradeName='S1' 
)
end


--上機題5


select studentname,(select GradeName from Grade)as Gradename,subjectname,examdate,studentresult from  Student,Subject,Result
where result.StudentNo in
(
   select MAX(ExamDate) from Result
   group by SubjectId
)


--上機題6
--SQL語句的綜合運用

--賦值科目名稱為oop
declare @subjectName varchar(50)
SET @subjectName='oop'
--科目為oop最近考試時間
declare @date datetime
select @date=MAX(examdate) from Result
inner join Subject on Result.SubjectId=Subject.SubjectId
where 
 
[email protected]
--課程oop的編號
declare @subjectNo int
select @subjectNo=SubjectId from Subject where [email protected]

--統計考試缺考情況

SELECT 應到人數=(
                 SELECT COUNT(*)  FROM Student 
                 INNER JOIN Subject ON Subject.GradeId=Student.GradeId 
                 WHERE SubjectName= @subjectName
                 ) ,
   
      實到人數=( 
                SELECT COUNT(*) FROM Result 
                WHERE 
 
[email protected] AND [email protected]
               ),
      缺考人數=(
                 SELECT COUNT(*)  FROM Student 
                 INNER JOIN Subject ON Subject.GradeId=Student.GradeId 
                 WHERE SubjectName= @subjectName
              ) -
              (
                 SELECT COUNT(*) FROM Result 
                 WHERE 
 
[email protected] AND [email protected]
              ) 

--統計考試通過情況，並將統計結果存放在新表TempResult中--
IF EXISTS(SELECT * FROM sysobjects WHERE name='TempResult')
  DROP TABLE TempResult

SELECT  Student.StudentName,Student.StudentNo,StudentResult,
        IsPass=CASE 
                 WHEN StudentResult>=60  THEN 1
                 ELSE 0
               END
 INTO TempResult 
FROM Student LEFT JOIN (
                         SELECT * FROM Result  WHERE [email protected] AND [email protected]
                        ) R
ON Student.StudentNo=R.StudentNo
WHERE GradeId=(SELECT GradeId FROM Subject WHERE SubjectName= @subjectName) 
      
SELECT * FROM TempResult 


DECLARE @avg numeric(4,1) 
SELECT @avg=AVG(StudentResult) FROM TempResult WHERE StudentResult IS NOT NULL

--判斷平均分是否低於60分。如果低於60分，設定平均分為60分
IF (@avg<60)  
 SET @avg=60
 
--迴圈加分，最高分不能超過97分
WHILE (1=1) 
BEGIN  
   IF(NOT Exists(SELECT * FROM TempResult WHERE StudentResult<@avg))
      BREAK
   ELSE
     UPDATE TempResult SET StudentResult=StudentResult+1
     WHERE StudentResult<@avg AND StudentResult<97
END


 --因為提分，所以需要更新IsPass（是否通過）列的資料
UPDATE TempResult 
  SET IsPass=CASE
               WHEN StudentResult>=60  THEN 1
               ELSE  0
            END

SELECT * FROM newTable

--顯示考試最終通過情況
SELECT 姓名=StudentName,學號=StudentNo, 
       成績=CASE 
              WHEN StudentResult IS NULL THEN '缺考'
              ELSE  CONVERT(varchar(5),StudentResult)
            END,
   是否通過=CASE 
              WHEN isPass=1 THEN '是'
              ELSE  '否'
           END
 FROM TempResult  

--顯示通過率及通過人數
SELECT 總人數=COUNT(*) ,通過人數=SUM(IsPass),
       通過率=(CONVERT(varchar(5),AVG(IsPass*100))+'%')  FROM TempResult 
GO

//經典案例


--參加oop最近一次考試時間的最高分數和最低分數
select MAX(studentresult), MIN(studentresult) from Result
where ExamDate=
(
select MAX(ExamDate) from Result 
where SubjectId=
(
select SubjectId from Subject where SubjectName='oop'
)
)
and SubjectId=
(
select SubjectId from Subject where SubjectName='oop'
)

----參加oop最近一次考試時間的學生姓名和學生編號

select studentno, studentname from Student
where StudentNo in
(
  select StudentNo from result 
  where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  and ExamDate=
  (
  select MAX(ExamDate) from Result 
  where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  )
)



--案例：檢查“oop”課程最近一次考試。--如果有分以上的成績，則每人提分；
	--否則，每人提分。最終的成績不得大於分


if exists(
 select studentresult from Result
   where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  and ExamDate=
  (
  select MAX(ExamDate) from Result 
  where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  )
 and StudentResult>80

)

begin
update Result set StudentResult=100
  where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  and ExamDate=
  (
  select MAX(ExamDate) from Result 
  where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  )
and StudentResult>98

update Result set StudentResult+=2
  where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  and ExamDate=
  (
  select MAX(ExamDate) from Result 
  where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  )
and StudentResult<=98
end

else

begin
update Result set StudentResult+=5
  where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  and ExamDate=
  (
  select MAX(ExamDate) from Result 
  where subjectid=
  (
   select subjectid from Subject where SubjectName='oop'
   
  )
  )

end