第四章高级查询--上机题和经典案例

--上机题1
--参加oop最近一次考试时间的最高分数和最低分数
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'
)


--上机题2

--使用in关键字的子查询来查询S1学期开设的课程


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


--上机题3

--查询某课程最近一次考试缺考的学生名单 

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'
)

--上机题4
--检查并更新S1的学生为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


--上机题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
)


--上机题6
--SQL语句的综合运用

--赋值科目名称为oop
declare @subjectName varchar(50)
SET @subjectName='oop'
--科目为oop最近考试时间
declare @date datetime
select @date=MAX(examdate) from Result
inner join Subject on Result.SubjectId=Subject.SubjectId
where SubjectName=@subjectName
--课程oop的编号
declare @subjectNo int
select @subjectNo=SubjectId from Subject where SubjectName=@subjectName

--统计考试缺考情况

SELECT 应到人数=(
                 SELECT COUNT(*)  FROM Student 
                 INNER JOIN Subject ON Subject.GradeId=Student.GradeId 
                 WHERE SubjectName= @subjectName
                 ) ,
   
      实到人数=( 
                SELECT COUNT(*) FROM Result 
                WHERE ExamDate=@date AND SubjectNo=@subjectNo
               ),
      缺考人数=(
                 SELECT COUNT(*)  FROM Student 
                 INNER JOIN Subject ON Subject.GradeId=Student.GradeId 
                 WHERE SubjectName= @subjectName
              ) -
              (
                 SELECT COUNT(*) FROM Result 
                 WHERE ExamDate=@date AND SubjectNo=@subjectNo
              ) 

--统计考试通过情况，并将统计结果存放在新表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 ExamDate=@date AND SubjectNo=@subjectNo
                        ) 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

--判断平均分是否低于60分。如果低于60分，设置平均分为60分
IF (@avg<60)  
 SET @avg=60
 
--循环加分，最高分不能超过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


 --因为提分，所以需要更新IsPass（是否通过）列的数据
UPDATE TempResult 
  SET IsPass=CASE
               WHEN StudentResult>=60  THEN 1
               ELSE  0
            END

SELECT * FROM newTable

--显示考试最终通过情况
SELECT 姓名=StudentName,学号=StudentNo, 
       成绩=CASE 
              WHEN StudentResult IS NULL THEN '缺考'
              ELSE  CONVERT(varchar(5),StudentResult)
            END,
   是否通过=CASE 
              WHEN isPass=1 THEN '是'
              ELSE  '否'
           END
 FROM TempResult  

--显示通过率及通过人数
SELECT 总人数=COUNT(*) ,通过人数=SUM(IsPass),
       通过率=(CONVERT(varchar(5),AVG(IsPass*100))+'%')  FROM TempResult 
GO

//经典案例


--参加oop最近一次考试时间的最高分数和最低分数
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'
)

----参加oop最近一次考试时间的学生姓名和学生编号

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：检查“oop”课程最近一次考试。--如果有分以上的成绩，则每人提分；
	--否则，每人提分。最终的成绩不得大于分


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