sql语句多表查询(学生表/课程表/教师表/成绩表 )
2013-08-10 22:22
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--问题及描述：
--1.学生表
--Student(S#,Sname,Sage,Ssex) --S# 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别
--2.课程表
--Course(C#,Cname,T#) --C# --课程编号,Cname 课程名称,T# 教师编号
--3.教师表
--Teacher(T#,Tname) --T# 教师编号,Tname 教师姓名
--4.成绩表
--SC(S#,C#,score) --S# 学生编号,C# 课程编号,score 分数
--创建测试数据
CREATE TABLE Student
(
S# VARCHAR(10) ,
Sname NVARCHAR(10) ,
Sage DATETIME ,
Ssex NVARCHAR(10)
)
INSERT INTO Student
VALUES ( '01', N'赵雷', '1990-01-01', N'男' )
INSERT INTO Student
VALUES ( '02', N'钱电', '1990-12-21', N'男' )
INSERT INTO Student
VALUES ( '03', N'孙风', '1990-05-20', N'男' )
INSERT INTO Student
VALUES ( '04', N'李云', '1990-08-06', N'男' )
INSERT INTO Student
VALUES ( '05', N'周梅', '1991-12-01', N'女' )
INSERT INTO Student
VALUES ( '06', N'吴兰', '1992-03-01', N'女' )
INSERT INTO Student
VALUES ( '07', N'郑竹', '1989-07-01', N'女' )
INSERT INTO Student
VALUES ( '08', N'王菊', '1990-01-20', N'女' )
CREATE TABLE Course
(
C# VARCHAR(10) ,
Cname NVARCHAR(10) ,
T# VARCHAR(10)
)
INSERT INTO Course
VALUES ( '01', N'语文', '02' )
INSERT INTO Course
VALUES ( '02', N'数学', '01' )
INSERT INTO Course
VALUES ( '03', N'英语', '03' )
CREATE TABLE Teacher
(
T# VARCHAR(10) ,
Tname NVARCHAR(10)
)
INSERT INTO Teacher
VALUES ( '01', N'张三' )
INSERT INTO Teacher
VALUES ( '02', N'李四' )
INSERT INTO Teacher
VALUES ( '03', N'王五' )
CREATE TABLE SC
(
S# VARCHAR(10) ,
C# VARCHAR(10) ,
score DECIMAL(18, 1)
)
INSERT INTO SC
VALUES ( '01', '01', 80 )
INSERT INTO SC
VALUES ( '01', '02', 90 )
INSERT INTO SC
VALUES ( '01', '03', 99 )
INSERT INTO SC
VALUES ( '02', '01', 70 )
INSERT INTO SC
VALUES ( '02', '02', 60 )
INSERT INTO SC
VALUES ( '02', '03', 80 )
INSERT INTO SC
VALUES ( '03', '01', 80 )
INSERT INTO SC
VALUES ( '03', '02', 80 )
INSERT INTO SC
VALUES ( '03', '03', 80 )
INSERT INTO SC
VALUES ( '04', '01', 50 )
INSERT INTO SC
VALUES ( '04', '02', 30 )
INSERT INTO SC
VALUES ( '04', '03', 20 )
INSERT INTO SC
VALUES ( '05', '01', 76 )
INSERT INTO SC
VALUES ( '05', '02', 87 )
INSERT INTO SC
VALUES ( '06', '01', 31 )
INSERT INTO SC
VALUES ( '06', '03', 34 )
INSERT INTO SC
VALUES ( '07', '02', 89 )
INSERT INTO SC
VALUES ( '07', '03', 98 )
go
--1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数
--1.1、查询同时存在"01"课程和"02"课程的情况
SELECT a.* ,
b.score [课程'01'的分数] ,
c.score [课程'02'的分数]
FROM Student a ,
SC b ,
SC c
WHERE a.S# = b.S#
AND a.S# = c.S#
AND b.C# = '01'
AND c.C# = '02'
AND b.score > c.score
--1.2、查询同时存在"01"课程和"02"课程的情况和存在"01"课程但可能不存在"02"课程的情况(不存在时显示为null)(以下存在相同内容时不再解释)
SELECT a.* ,
b.score [课程"01"的分数] ,
c.score [课程"02"的分数]
FROM Student a
LEFT JOIN SC b ON a.S# = b.S#
AND b.C# = '01'
LEFT JOIN SC c ON a.S# = c.S#
AND c.C# = '02'
WHERE b.score > ISNULL(c.score, 0)
--2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
--2.1、查询同时存在"01"课程和"02"课程的情况
SELECT a.* ,
b.score [课程'01'的分数] ,
c.score [课程'02'的分数]
FROM Student a ,
SC b ,
SC c
WHERE a.S# = b.S#
AND a.S# = c.S#
AND b.C# = '01'
AND c.C# = '02'
AND b.score < c.score
--2.2、查询同时存在"01"课程和"02"课程的情况和不存在"01"课程但存在"02"课程的情况
SELECT a.* ,
b.score [课程"01"的分数] ,
c.score [课程"02"的分数]
FROM Student a
LEFT JOIN SC b ON a.S# = b.S#
AND b.C# = '01'
LEFT JOIN SC c ON a.S# = c.S#
AND c.C# = '02'
WHERE ISNULL(b.score, 0) < c.score
--3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
SELECT a.S# ,
a.Sname ,
CAST(AVG(b.score) AS DECIMAL(18, 2)) avg_score
FROM Student a ,
sc b
WHERE a.S# = b.S#
GROUP BY a.S# ,
a.Sname
HAVING CAST(AVG(b.score) AS DECIMAL(18, 2)) >= 60
ORDER BY a.S#
--4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩
--4.1、查询在sc表存在成绩的学生信息的SQL语句。
SELECT a.S# ,
a.Sname ,
CAST(AVG(b.score) AS DECIMAL(18, 2)) avg_score
FROM Student a ,
sc b
WHERE a.S# = b.S#
GROUP BY a.S# ,
a.Sname
HAVING CAST(AVG(b.score) AS DECIMAL(18, 2)) < 60
ORDER BY a.S#
--4.2、查询在sc表中不存在成绩的学生信息的SQL语句。
SELECT a.S# ,
a.Sname ,
ISNULL(CAST(AVG(b.score) AS DECIMAL(18, 2)), 0) avg_score
FROM Student a
LEFT JOIN sc b ON a.S# = b.S#
GROUP BY a.S# ,
a.Sname
HAVING ISNULL(CAST(AVG(b.score) AS DECIMAL(18, 2)), 0) < 60
ORDER BY a.S#
--5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
--5.1、查询所有有成绩的SQL。
SELECT a.S# [学生编号] ,
a.Sname [学生姓名] ,
COUNT(b.C#) 选课总数 ,
SUM(score) [所有课程的总成绩]
FROM Student a ,
SC b
WHERE a.S# = b.S#
GROUP BY a.S# ,
a.Sname
ORDER BY a.S#
--5.2、查询所有(包括有成绩和无成绩)的SQL。
SELECT a.S# [学生编号] ,
a.Sname [学生姓名] ,
COUNT(b.C#) 选课总数 ,
SUM(score) [所有课程的总成绩]
FROM Student a
LEFT JOIN SC b ON a.S# = b.S#
GROUP BY a.S# ,
a.Sname
ORDER BY a.S#
--6、查询"李"姓老师的数量
--方法1
SELECT COUNT(Tname) ["李"姓老师的数量]
FROM Teacher
WHERE Tname LIKE N'李%'
--方法2
SELECT COUNT(Tname) ["李"姓老师的数量]
FROM Teacher
WHERE LEFT(Tname, 1) = N'李'
--7、查询学过"张三"老师授课的同学的信息
SELECT DISTINCT
Student.*
FROM Student ,
SC ,
Course ,
Teacher
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三'
ORDER BY Student.S#
--8、查询没学过"张三"老师授课的同学的信息
SELECT m.*
FROM Student m
WHERE S# NOT IN ( SELECT DISTINCT
SC.S#
FROM SC ,
Course ,
Teacher
WHERE SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三' )
ORDER BY m.S#
--9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
--方法1
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# = '01'
AND EXISTS ( SELECT 1
FROM SC SC_2
WHERE SC_2.S# = SC.S#
AND SC_2.C# = '02' )
ORDER BY Student.S#
--方法2
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# = '02'
AND EXISTS ( SELECT 1
FROM SC SC_2
WHERE SC_2.S# = SC.S#
AND SC_2.C# = '01' )
ORDER BY Student.S#
--方法3
SELECT m.*
FROM Student m
WHERE S# IN ( SELECT S#
FROM ( SELECT DISTINCT
S#
FROM SC
WHERE C# = '01'
UNION ALL
SELECT DISTINCT
S#
FROM SC
WHERE C# = '02'
) t
GROUP BY S#
HAVING COUNT(1) = 2 )
ORDER BY m.S#
--10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
--方法1
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# = '01'
AND NOT EXISTS ( SELECT 1
FROM SC SC_2
WHERE SC_2.S# = SC.S#
AND SC_2.C# = '02' )
ORDER BY Student.S#
--方法2
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# = '01'
AND Student.S# NOT IN ( SELECT SC_2.S#
FROM SC SC_2
WHERE SC_2.S# = SC.S#
AND SC_2.C# = '02' )
ORDER BY Student.S#
--11、查询没有学全所有课程的同学的信息
--11.1、
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
GROUP BY Student.S# ,
Student.Sname ,
Student.Sage ,
Student.Ssex
HAVING COUNT(C#) < ( SELECT COUNT(C#)
FROM Course
)
--11.2
SELECT Student.*
FROM Student
LEFT JOIN SC ON Student.S# = SC.S#
GROUP BY Student.S# ,
Student.Sname ,
Student.Sage ,
Student.Ssex
HAVING COUNT(C#) < ( SELECT COUNT(C#)
FROM Course
)
--12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息
SELECT DISTINCT
Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# IN ( SELECT C#
FROM SC
WHERE S# = '01' )
AND Student.S# <> '01'
--13、查询和"01"号的同学学习的课程完全相同的其他同学的信息
SELECT Student.*
FROM Student
WHERE S# IN ( SELECT DISTINCT
SC.S#
FROM SC
WHERE S# <> '01'
AND SC.C# IN ( SELECT DISTINCT
C#
FROM SC
WHERE S# = '01' )
GROUP BY SC.S#
HAVING COUNT(1) = ( SELECT COUNT(1)
FROM SC
WHERE S# = '01'
) )
--14、查询没学过"张三"老师讲授的任一门课程的学生姓名
SELECT student.*
FROM student
WHERE student.S# NOT IN ( SELECT DISTINCT
sc.S#
FROM sc ,
course ,
teacher
WHERE sc.C# = course.C#
AND course.T# = teacher.T#
AND teacher.tname = N'张三' )
ORDER BY student.S#
--15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
SELECT student.S# ,
student.sname ,
CAST(AVG(score) AS DECIMAL(18, 2)) avg_score
FROM student ,
sc
WHERE student.S# = SC.S#
AND student.S# IN ( SELECT S#
FROM SC
WHERE score < 60
GROUP BY S#
HAVING COUNT(1) >= 2 )
GROUP BY student.S# ,
student.sname
--16、检索"01"课程分数小于60，按分数降序排列的学生信息
SELECT student.* ,
sc.C# ,
sc.score
FROM student ,
sc
WHERE student.S# = SC.S#
AND sc.score < 60
AND sc.C# = '01'
ORDER BY sc.score DESC
--17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
--17.1 SQL 2000 静态
SELECT a.S# 学生编号 ,
a.Sname 学生姓名 ,
MAX(CASE c.Cname
WHEN N'语文' THEN b.score
ELSE NULL
END) [语文] ,
MAX(CASE c.Cname
WHEN N'数学' THEN b.score
ELSE NULL
END) [数学] ,
MAX(CASE c.Cname
WHEN N'英语' THEN b.score
ELSE NULL
END) [英语] ,
CAST(AVG(b.score) AS DECIMAL(18, 2)) 平均分
FROM Student a
LEFT JOIN SC b ON a.S# = b.S#
LEFT JOIN Course c ON b.C# = c.C#
GROUP BY a.S# ,
a.Sname
ORDER BY 平均分 DESC
--17.2 SQL 2000 动态
DECLARE @sql NVARCHAR(4000)
SET @sql = 'select a.S# ' + N'学生编号' + ' , a.Sname ' + N'学生姓名'
SELECT @sql = @sql + ',max(case c.Cname when N''' + Cname
+ ''' then b.score else null end) [' + Cname + ']'
FROM ( SELECT DISTINCT
Cname
FROM Course
) AS t
SET @sql = @sql + ' , cast(avg(b.score) as decimal(18,2)) ' + N'平均分'
+ ' from Student a left join SC b on a.S# = b.S# left join Course c on b.C# = c.C#
group by a.S# , a.Sname order by ' + N'平均分' + ' desc'
EXEC(@sql)
--24、查询学生平均成绩及其名次
--24.1 查询学生的平均成绩并进行排名，sql 2000用子查询完成，分平均成绩重复时保留名次空缺和不保留名次空缺两种。
SELECT t1.* ,
px = ( SELECT COUNT(1)
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)),
0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t2
WHERE 平均成绩 > t1.平均成绩
) + 1
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)), 0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t1
ORDER BY px
SELECT t1.* ,
px = ( SELECT COUNT(DISTINCT 平均成绩)
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)),
0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t2
WHERE 平均成绩 >= t1.平均成绩
)
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)), 0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t1
ORDER BY px
--24.2 查询学生的平均成绩并进行排名，sql 2005用rank,DENSE_RANK完成，分平均成绩重复时保留名次空缺和不保留名次空缺两种。
SELECT t.* ,
px = RANK() OVER ( ORDER BY [平均成绩] DESC )
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)), 0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t
ORDER BY px
SELECT t.* ,
px = DENSE_RANK() OVER ( ORDER BY [平均成绩] DESC )
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)), 0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t
ORDER BY px
--25、查询各科成绩前三名的记录
--25.1 分数重复时保留名次空缺
SELECT m.* ,
n.C# ,
n.score
FROM Student m ,
SC n
WHERE m.S# = n.S#
AND n.score IN ( SELECT TOP 3
score
FROM sc
WHERE C# = n.C#
ORDER BY score DESC )
ORDER BY n.C# ,
n.score DESC
--25.2 分数重复时不保留名次空缺，合并名次
--sql 2000用子查询实现
SELECT *
FROM ( SELECT t.* ,
px = ( SELECT COUNT(DISTINCT score)
FROM SC
WHERE C# = t.C#
AND score >= t.score
)
FROM sc t
) m
WHERE px BETWEEN 1 AND 3
ORDER BY m.c# ,
m.px
--sql 2005用DENSE_RANK实现
SELECT *
FROM ( SELECT t.* ,
px = DENSE_RANK() OVER ( PARTITION BY c# ORDER BY score DESC )
FROM sc t
) m
WHERE px BETWEEN 1 AND 3
ORDER BY m.C# ,
m.px
--26、查询每门课程被选修的学生数
SELECT c# ,
COUNT(S#) [学生数]
FROM sc
GROUP BY C#
--27、查询出只有两门课程的全部学生的学号和姓名
SELECT Student.S# ,
Student.Sname
FROM Student ,
SC
WHERE Student.S# = SC.S#
GROUP BY Student.S# ,
Student.Sname
HAVING COUNT(SC.C#) = 2
ORDER BY Student.S#
--28、查询男生、女生人数
SELECT COUNT(Ssex) AS 男生人数
FROM Student
WHERE Ssex = N'男'
SELECT COUNT(Ssex) AS 女生人数
FROM Student
WHERE Ssex = N'女'
SELECT SUM(CASE WHEN Ssex = N'男' THEN 1
ELSE 0
END) [男生人数] ,
SUM(CASE WHEN Ssex = N'女' THEN 1
ELSE 0
END) [女生人数]
FROM student
SELECT CASE WHEN Ssex = N'男' THEN N'男生人数'
ELSE N'女生人数'
END [男女情况] ,
COUNT(1) [人数]
FROM student
GROUP BY CASE WHEN Ssex = N'男' THEN N'男生人数'
ELSE N'女生人数'
END
--29、查询名字中含有"风"字的学生信息
SELECT *
FROM student
WHERE sname LIKE N'%风%'
SELECT *
FROM student
WHERE CHARINDEX(N'风', sname) > 0
--30、查询同名同性学生名单，并统计同名人数
SELECT Sname [学生姓名] ,
COUNT(*) [人数]
FROM Student
GROUP BY Sname
HAVING COUNT(*) > 1
--31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime)
SELECT *
FROM Student
WHERE YEAR(sage) = 1990
SELECT *
FROM Student
WHERE DATEDIFF(yy, sage, '1990-01-01') = 0
SELECT *
FROM Student
WHERE DATEPART(yy, sage) = 1990
SELECT *
FROM Student
WHERE CONVERT(VARCHAR(4), sage, 120) = '1990'
--32、查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列
SELECT m.C# ,
m.Cname ,
CAST(AVG(n.score) AS DECIMAL(18, 2)) avg_score
FROM Course m ,
SC n
WHERE m.C# = n.C#
GROUP BY m.C# ,
m.Cname
ORDER BY avg_score DESC ,
m.C# ASC
--33、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩
SELECT a.S# ,
a.Sname ,
CAST(AVG(b.score) AS DECIMAL(18, 2)) avg_score
FROM Student a ,
sc b
WHERE a.S# = b.S#
GROUP BY a.S# ,
a.Sname
HAVING CAST(AVG(b.score) AS DECIMAL(18, 2)) >= 85
ORDER BY a.S#
--34、查询课程名称为"数学"，且分数低于60的学生姓名和分数
SELECT sname ,
score
FROM Student ,
SC ,
Course
WHERE SC.S# = Student.S#
AND SC.C# = Course.C#
AND Course.Cname = N'数学'
AND score < 60
--35、查询所有学生的课程及分数情况；
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
ORDER BY Student.S# ,
SC.C#
--36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND SC.score >= 70
ORDER BY Student.S# ,
SC.C#
--37、查询不及格的课程
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND SC.score < 60
ORDER BY Student.S# ,
SC.C#
--38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名；
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND SC.C# = '01'
AND SC.score >= 80
ORDER BY Student.S# ,
SC.C#
--39、求每门课程的学生人数
SELECT Course.C# ,
Course.Cname ,
COUNT(*) [学生人数]
FROM Course ,
SC
WHERE Course.C# = SC.C#
GROUP BY Course.C# ,
Course.Cname
ORDER BY Course.C# ,
Course.Cname
--40、查询选修"张三"老师所授课程的学生中，成绩最高的学生信息及其成绩
--40.1 当最高分只有一个时
SELECT TOP 1
Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course ,
Teacher
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三'
ORDER BY SC.score DESC
--40.2 当最高分出现多个时
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course ,
Teacher
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三'
AND SC.score = ( SELECT MAX(SC.score)
FROM SC ,
Course ,
Teacher
WHERE SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三'
)
--41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
--方法1
SELECT m.*
FROM SC m ,
( SELECT C# ,
score
FROM SC
GROUP BY C# ,
score
HAVING COUNT(1) > 1
) n
WHERE m.C# = n.C#
AND m.score = n.score
ORDER BY m.C# ,
m.score ,
m.S#
--方法2
SELECT m.*
FROM SC m
WHERE EXISTS ( SELECT 1
FROM ( SELECT C# ,
score
FROM SC
GROUP BY C# ,
score
HAVING COUNT(1) > 1
) n
WHERE m.C# = n.C#
AND m.score = n.score )
ORDER BY m.C# ,
m.score ,
m.S#
--42、查询每门功成绩最好的前两名
SELECT t.*
FROM sc t
WHERE score IN ( SELECT TOP 2
score
FROM sc
WHERE C# = T.C#
ORDER BY score DESC )
ORDER BY t.C# ,
t.score DESC
--43、统计每门课程的学生选修人数（超过5人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列
SELECT Course.C# ,
Course.Cname ,
COUNT(*) [学生人数]
FROM Course ,
SC
WHERE Course.C# = SC.C#
GROUP BY Course.C# ,
Course.Cname
HAVING COUNT(*) >= 5
ORDER BY [学生人数] DESC ,
Course.C#
--44、检索至少选修两门课程的学生学号
SELECT student.S# ,
student.Sname
FROM student ,
SC
WHERE student.S# = SC.S#
GROUP BY student.S# ,
student.Sname
HAVING COUNT(1) >= 2
ORDER BY student.S#
--45、查询选修了全部课程的学生信息
--方法1 根据数量来完成
SELECT student.*
FROM student
WHERE S# IN ( SELECT S#
FROM sc
GROUP BY S#
HAVING COUNT(1) = ( SELECT COUNT(1)
FROM course
) )
--方法2 使用双重否定来完成
SELECT t.*
FROM student t
WHERE t.S# NOT IN ( SELECT DISTINCT
m.S#
FROM ( SELECT S# ,
C#
FROM student ,
course
) m
WHERE NOT EXISTS ( SELECT 1
FROM sc n
WHERE n.S# = m.S#
AND n.C# = m.C# ) )
--方法3 使用双重否定来完成
SELECT t.*
FROM student t
WHERE NOT EXISTS ( SELECT 1
FROM ( SELECT DISTINCT
m.S#
FROM ( SELECT S# ,
C#
FROM student ,
course
) m
WHERE NOT EXISTS ( SELECT 1
FROM sc n
WHERE n.S# = m.S#
AND n.C# = m.C# )
) k
WHERE k.S# = t.S# )
--46、查询各学生的年龄
--46.1 只按照年份来算
SELECT * ,
DATEDIFF(yy, sage, GETDATE()) [年龄]
FROM student
--46.2 按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一
SELECT * ,
CASE WHEN RIGHT(CONVERT(VARCHAR(10), GETDATE(), 120), 5) < RIGHT(CONVERT(VARCHAR(10), sage, 120),
5)
THEN DATEDIFF(yy, sage, GETDATE()) - 1
ELSE DATEDIFF(yy, sage, GETDATE())
END [年龄]
FROM student
--47、查询本周过生日的学生
SELECT *
FROM student
WHERE DATEDIFF(week,
DATENAME(yy, GETDATE()) + RIGHT(CONVERT(VARCHAR(10), sage, 120),
6), GETDATE()) = 0
--48、查询下周过生日的学生
SELECT *
FROM student
WHERE DATEDIFF(week,
DATENAME(yy, GETDATE()) + RIGHT(CONVERT(VARCHAR(10), sage, 120),
6), GETDATE()) = -1
--49、查询本月过生日的学生
SELECT *
FROM student
WHERE DATEDIFF(mm,
DATENAME(yy, GETDATE()) + RIGHT(CONVERT(VARCHAR(10), sage, 120),
6), GETDATE()) = 0
--50、查询下月过生日的学生
SELECT *
FROM student
WHERE DATEDIFF(mm,
DATENAME(yy, GETDATE()) + RIGHT(CONVERT(VARCHAR(10), sage, 120),
6), GETDATE()) = -1
DROP TABLE Student,Course,Teacher,SC
--1.学生表
--Student(S#,Sname,Sage,Ssex) --S# 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别
--2.课程表
--Course(C#,Cname,T#) --C# --课程编号,Cname 课程名称,T# 教师编号
--3.教师表
--Teacher(T#,Tname) --T# 教师编号,Tname 教师姓名
--4.成绩表
--SC(S#,C#,score) --S# 学生编号,C# 课程编号,score 分数
--创建测试数据
CREATE TABLE Student
(
S# VARCHAR(10) ,
Sname NVARCHAR(10) ,
Sage DATETIME ,
Ssex NVARCHAR(10)
)
INSERT INTO Student
VALUES ( '01', N'赵雷', '1990-01-01', N'男' )
INSERT INTO Student
VALUES ( '02', N'钱电', '1990-12-21', N'男' )
INSERT INTO Student
VALUES ( '03', N'孙风', '1990-05-20', N'男' )
INSERT INTO Student
VALUES ( '04', N'李云', '1990-08-06', N'男' )
INSERT INTO Student
VALUES ( '05', N'周梅', '1991-12-01', N'女' )
INSERT INTO Student
VALUES ( '06', N'吴兰', '1992-03-01', N'女' )
INSERT INTO Student
VALUES ( '07', N'郑竹', '1989-07-01', N'女' )
INSERT INTO Student
VALUES ( '08', N'王菊', '1990-01-20', N'女' )
CREATE TABLE Course
(
C# VARCHAR(10) ,
Cname NVARCHAR(10) ,
T# VARCHAR(10)
)
INSERT INTO Course
VALUES ( '01', N'语文', '02' )
INSERT INTO Course
VALUES ( '02', N'数学', '01' )
INSERT INTO Course
VALUES ( '03', N'英语', '03' )
CREATE TABLE Teacher
(
T# VARCHAR(10) ,
Tname NVARCHAR(10)
)
INSERT INTO Teacher
VALUES ( '01', N'张三' )
INSERT INTO Teacher
VALUES ( '02', N'李四' )
INSERT INTO Teacher
VALUES ( '03', N'王五' )
CREATE TABLE SC
(
S# VARCHAR(10) ,
C# VARCHAR(10) ,
score DECIMAL(18, 1)
)
INSERT INTO SC
VALUES ( '01', '01', 80 )
INSERT INTO SC
VALUES ( '01', '02', 90 )
INSERT INTO SC
VALUES ( '01', '03', 99 )
INSERT INTO SC
VALUES ( '02', '01', 70 )
INSERT INTO SC
VALUES ( '02', '02', 60 )
INSERT INTO SC
VALUES ( '02', '03', 80 )
INSERT INTO SC
VALUES ( '03', '01', 80 )
INSERT INTO SC
VALUES ( '03', '02', 80 )
INSERT INTO SC
VALUES ( '03', '03', 80 )
INSERT INTO SC
VALUES ( '04', '01', 50 )
INSERT INTO SC
VALUES ( '04', '02', 30 )
INSERT INTO SC
VALUES ( '04', '03', 20 )
INSERT INTO SC
VALUES ( '05', '01', 76 )
INSERT INTO SC
VALUES ( '05', '02', 87 )
INSERT INTO SC
VALUES ( '06', '01', 31 )
INSERT INTO SC
VALUES ( '06', '03', 34 )
INSERT INTO SC
VALUES ( '07', '02', 89 )
INSERT INTO SC
VALUES ( '07', '03', 98 )
go
--1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数
--1.1、查询同时存在"01"课程和"02"课程的情况
SELECT a.* ,
b.score [课程'01'的分数] ,
c.score [课程'02'的分数]
FROM Student a ,
SC b ,
SC c
WHERE a.S# = b.S#
AND a.S# = c.S#
AND b.C# = '01'
AND c.C# = '02'
AND b.score > c.score
--1.2、查询同时存在"01"课程和"02"课程的情况和存在"01"课程但可能不存在"02"课程的情况(不存在时显示为null)(以下存在相同内容时不再解释)
SELECT a.* ,
b.score [课程"01"的分数] ,
c.score [课程"02"的分数]
FROM Student a
LEFT JOIN SC b ON a.S# = b.S#
AND b.C# = '01'
LEFT JOIN SC c ON a.S# = c.S#
AND c.C# = '02'
WHERE b.score > ISNULL(c.score, 0)
--2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
--2.1、查询同时存在"01"课程和"02"课程的情况
SELECT a.* ,
b.score [课程'01'的分数] ,
c.score [课程'02'的分数]
FROM Student a ,
SC b ,
SC c
WHERE a.S# = b.S#
AND a.S# = c.S#
AND b.C# = '01'
AND c.C# = '02'
AND b.score < c.score
--2.2、查询同时存在"01"课程和"02"课程的情况和不存在"01"课程但存在"02"课程的情况
SELECT a.* ,
b.score [课程"01"的分数] ,
c.score [课程"02"的分数]
FROM Student a
LEFT JOIN SC b ON a.S# = b.S#
AND b.C# = '01'
LEFT JOIN SC c ON a.S# = c.S#
AND c.C# = '02'
WHERE ISNULL(b.score, 0) < c.score
--3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
SELECT a.S# ,
a.Sname ,
CAST(AVG(b.score) AS DECIMAL(18, 2)) avg_score
FROM Student a ,
sc b
WHERE a.S# = b.S#
GROUP BY a.S# ,
a.Sname
HAVING CAST(AVG(b.score) AS DECIMAL(18, 2)) >= 60
ORDER BY a.S#
--4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩
--4.1、查询在sc表存在成绩的学生信息的SQL语句。
SELECT a.S# ,
a.Sname ,
CAST(AVG(b.score) AS DECIMAL(18, 2)) avg_score
FROM Student a ,
sc b
WHERE a.S# = b.S#
GROUP BY a.S# ,
a.Sname
HAVING CAST(AVG(b.score) AS DECIMAL(18, 2)) < 60
ORDER BY a.S#
--4.2、查询在sc表中不存在成绩的学生信息的SQL语句。
SELECT a.S# ,
a.Sname ,
ISNULL(CAST(AVG(b.score) AS DECIMAL(18, 2)), 0) avg_score
FROM Student a
LEFT JOIN sc b ON a.S# = b.S#
GROUP BY a.S# ,
a.Sname
HAVING ISNULL(CAST(AVG(b.score) AS DECIMAL(18, 2)), 0) < 60
ORDER BY a.S#
--5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
--5.1、查询所有有成绩的SQL。
SELECT a.S# [学生编号] ,
a.Sname [学生姓名] ,
COUNT(b.C#) 选课总数 ,
SUM(score) [所有课程的总成绩]
FROM Student a ,
SC b
WHERE a.S# = b.S#
GROUP BY a.S# ,
a.Sname
ORDER BY a.S#
--5.2、查询所有(包括有成绩和无成绩)的SQL。
SELECT a.S# [学生编号] ,
a.Sname [学生姓名] ,
COUNT(b.C#) 选课总数 ,
SUM(score) [所有课程的总成绩]
FROM Student a
LEFT JOIN SC b ON a.S# = b.S#
GROUP BY a.S# ,
a.Sname
ORDER BY a.S#
--6、查询"李"姓老师的数量
--方法1
SELECT COUNT(Tname) ["李"姓老师的数量]
FROM Teacher
WHERE Tname LIKE N'李%'
--方法2
SELECT COUNT(Tname) ["李"姓老师的数量]
FROM Teacher
WHERE LEFT(Tname, 1) = N'李'
--7、查询学过"张三"老师授课的同学的信息
SELECT DISTINCT
Student.*
FROM Student ,
SC ,
Course ,
Teacher
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三'
ORDER BY Student.S#
--8、查询没学过"张三"老师授课的同学的信息
SELECT m.*
FROM Student m
WHERE S# NOT IN ( SELECT DISTINCT
SC.S#
FROM SC ,
Course ,
Teacher
WHERE SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三' )
ORDER BY m.S#
--9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
--方法1
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# = '01'
AND EXISTS ( SELECT 1
FROM SC SC_2
WHERE SC_2.S# = SC.S#
AND SC_2.C# = '02' )
ORDER BY Student.S#
--方法2
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# = '02'
AND EXISTS ( SELECT 1
FROM SC SC_2
WHERE SC_2.S# = SC.S#
AND SC_2.C# = '01' )
ORDER BY Student.S#
--方法3
SELECT m.*
FROM Student m
WHERE S# IN ( SELECT S#
FROM ( SELECT DISTINCT
S#
FROM SC
WHERE C# = '01'
UNION ALL
SELECT DISTINCT
S#
FROM SC
WHERE C# = '02'
) t
GROUP BY S#
HAVING COUNT(1) = 2 )
ORDER BY m.S#
--10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
--方法1
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# = '01'
AND NOT EXISTS ( SELECT 1
FROM SC SC_2
WHERE SC_2.S# = SC.S#
AND SC_2.C# = '02' )
ORDER BY Student.S#
--方法2
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# = '01'
AND Student.S# NOT IN ( SELECT SC_2.S#
FROM SC SC_2
WHERE SC_2.S# = SC.S#
AND SC_2.C# = '02' )
ORDER BY Student.S#
--11、查询没有学全所有课程的同学的信息
--11.1、
SELECT Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
GROUP BY Student.S# ,
Student.Sname ,
Student.Sage ,
Student.Ssex
HAVING COUNT(C#) < ( SELECT COUNT(C#)
FROM Course
)
--11.2
SELECT Student.*
FROM Student
LEFT JOIN SC ON Student.S# = SC.S#
GROUP BY Student.S# ,
Student.Sname ,
Student.Sage ,
Student.Ssex
HAVING COUNT(C#) < ( SELECT COUNT(C#)
FROM Course
)
--12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息
SELECT DISTINCT
Student.*
FROM Student ,
SC
WHERE Student.S# = SC.S#
AND SC.C# IN ( SELECT C#
FROM SC
WHERE S# = '01' )
AND Student.S# <> '01'
--13、查询和"01"号的同学学习的课程完全相同的其他同学的信息
SELECT Student.*
FROM Student
WHERE S# IN ( SELECT DISTINCT
SC.S#
FROM SC
WHERE S# <> '01'
AND SC.C# IN ( SELECT DISTINCT
C#
FROM SC
WHERE S# = '01' )
GROUP BY SC.S#
HAVING COUNT(1) = ( SELECT COUNT(1)
FROM SC
WHERE S# = '01'
) )
--14、查询没学过"张三"老师讲授的任一门课程的学生姓名
SELECT student.*
FROM student
WHERE student.S# NOT IN ( SELECT DISTINCT
sc.S#
FROM sc ,
course ,
teacher
WHERE sc.C# = course.C#
AND course.T# = teacher.T#
AND teacher.tname = N'张三' )
ORDER BY student.S#
--15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
SELECT student.S# ,
student.sname ,
CAST(AVG(score) AS DECIMAL(18, 2)) avg_score
FROM student ,
sc
WHERE student.S# = SC.S#
AND student.S# IN ( SELECT S#
FROM SC
WHERE score < 60
GROUP BY S#
HAVING COUNT(1) >= 2 )
GROUP BY student.S# ,
student.sname
--16、检索"01"课程分数小于60，按分数降序排列的学生信息
SELECT student.* ,
sc.C# ,
sc.score
FROM student ,
sc
WHERE student.S# = SC.S#
AND sc.score < 60
AND sc.C# = '01'
ORDER BY sc.score DESC
--17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
--17.1 SQL 2000 静态
SELECT a.S# 学生编号 ,
a.Sname 学生姓名 ,
MAX(CASE c.Cname
WHEN N'语文' THEN b.score
ELSE NULL
END) [语文] ,
MAX(CASE c.Cname
WHEN N'数学' THEN b.score
ELSE NULL
END) [数学] ,
MAX(CASE c.Cname
WHEN N'英语' THEN b.score
ELSE NULL
END) [英语] ,
CAST(AVG(b.score) AS DECIMAL(18, 2)) 平均分
FROM Student a
LEFT JOIN SC b ON a.S# = b.S#
LEFT JOIN Course c ON b.C# = c.C#
GROUP BY a.S# ,
a.Sname
ORDER BY 平均分 DESC
--17.2 SQL 2000 动态
DECLARE @sql NVARCHAR(4000)
SET @sql = 'select a.S# ' + N'学生编号' + ' , a.Sname ' + N'学生姓名'
SELECT @sql = @sql + ',max(case c.Cname when N''' + Cname
+ ''' then b.score else null end) [' + Cname + ']'
FROM ( SELECT DISTINCT
Cname
FROM Course
) AS t
SET @sql = @sql + ' , cast(avg(b.score) as decimal(18,2)) ' + N'平均分'
+ ' from Student a left join SC b on a.S# = b.S# left join Course c on b.C# = c.C#
group by a.S# , a.Sname order by ' + N'平均分' + ' desc'
EXEC(@sql)
--24、查询学生平均成绩及其名次
--24.1 查询学生的平均成绩并进行排名，sql 2000用子查询完成，分平均成绩重复时保留名次空缺和不保留名次空缺两种。
SELECT t1.* ,
px = ( SELECT COUNT(1)
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)),
0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t2
WHERE 平均成绩 > t1.平均成绩
) + 1
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)), 0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t1
ORDER BY px
SELECT t1.* ,
px = ( SELECT COUNT(DISTINCT 平均成绩)
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)),
0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t2
WHERE 平均成绩 >= t1.平均成绩
)
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)), 0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t1
ORDER BY px
--24.2 查询学生的平均成绩并进行排名，sql 2005用rank,DENSE_RANK完成，分平均成绩重复时保留名次空缺和不保留名次空缺两种。
SELECT t.* ,
px = RANK() OVER ( ORDER BY [平均成绩] DESC )
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)), 0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t
ORDER BY px
SELECT t.* ,
px = DENSE_RANK() OVER ( ORDER BY [平均成绩] DESC )
FROM ( SELECT m.S# [学生编号] ,
m.Sname [学生姓名] ,
ISNULL(CAST(AVG(score) AS DECIMAL(18, 2)), 0) [平均成绩]
FROM Student m
LEFT JOIN SC n ON m.S# = n.S#
GROUP BY m.S# ,
m.Sname
) t
ORDER BY px
--25、查询各科成绩前三名的记录
--25.1 分数重复时保留名次空缺
SELECT m.* ,
n.C# ,
n.score
FROM Student m ,
SC n
WHERE m.S# = n.S#
AND n.score IN ( SELECT TOP 3
score
FROM sc
WHERE C# = n.C#
ORDER BY score DESC )
ORDER BY n.C# ,
n.score DESC
--25.2 分数重复时不保留名次空缺，合并名次
--sql 2000用子查询实现
SELECT *
FROM ( SELECT t.* ,
px = ( SELECT COUNT(DISTINCT score)
FROM SC
WHERE C# = t.C#
AND score >= t.score
)
FROM sc t
) m
WHERE px BETWEEN 1 AND 3
ORDER BY m.c# ,
m.px
--sql 2005用DENSE_RANK实现
SELECT *
FROM ( SELECT t.* ,
px = DENSE_RANK() OVER ( PARTITION BY c# ORDER BY score DESC )
FROM sc t
) m
WHERE px BETWEEN 1 AND 3
ORDER BY m.C# ,
m.px
--26、查询每门课程被选修的学生数
SELECT c# ,
COUNT(S#) [学生数]
FROM sc
GROUP BY C#
--27、查询出只有两门课程的全部学生的学号和姓名
SELECT Student.S# ,
Student.Sname
FROM Student ,
SC
WHERE Student.S# = SC.S#
GROUP BY Student.S# ,
Student.Sname
HAVING COUNT(SC.C#) = 2
ORDER BY Student.S#
--28、查询男生、女生人数
SELECT COUNT(Ssex) AS 男生人数
FROM Student
WHERE Ssex = N'男'
SELECT COUNT(Ssex) AS 女生人数
FROM Student
WHERE Ssex = N'女'
SELECT SUM(CASE WHEN Ssex = N'男' THEN 1
ELSE 0
END) [男生人数] ,
SUM(CASE WHEN Ssex = N'女' THEN 1
ELSE 0
END) [女生人数]
FROM student
SELECT CASE WHEN Ssex = N'男' THEN N'男生人数'
ELSE N'女生人数'
END [男女情况] ,
COUNT(1) [人数]
FROM student
GROUP BY CASE WHEN Ssex = N'男' THEN N'男生人数'
ELSE N'女生人数'
END
--29、查询名字中含有"风"字的学生信息
SELECT *
FROM student
WHERE sname LIKE N'%风%'
SELECT *
FROM student
WHERE CHARINDEX(N'风', sname) > 0
--30、查询同名同性学生名单，并统计同名人数
SELECT Sname [学生姓名] ,
COUNT(*) [人数]
FROM Student
GROUP BY Sname
HAVING COUNT(*) > 1
--31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime)
SELECT *
FROM Student
WHERE YEAR(sage) = 1990
SELECT *
FROM Student
WHERE DATEDIFF(yy, sage, '1990-01-01') = 0
SELECT *
FROM Student
WHERE DATEPART(yy, sage) = 1990
SELECT *
FROM Student
WHERE CONVERT(VARCHAR(4), sage, 120) = '1990'
--32、查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列
SELECT m.C# ,
m.Cname ,
CAST(AVG(n.score) AS DECIMAL(18, 2)) avg_score
FROM Course m ,
SC n
WHERE m.C# = n.C#
GROUP BY m.C# ,
m.Cname
ORDER BY avg_score DESC ,
m.C# ASC
--33、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩
SELECT a.S# ,
a.Sname ,
CAST(AVG(b.score) AS DECIMAL(18, 2)) avg_score
FROM Student a ,
sc b
WHERE a.S# = b.S#
GROUP BY a.S# ,
a.Sname
HAVING CAST(AVG(b.score) AS DECIMAL(18, 2)) >= 85
ORDER BY a.S#
--34、查询课程名称为"数学"，且分数低于60的学生姓名和分数
SELECT sname ,
score
FROM Student ,
SC ,
Course
WHERE SC.S# = Student.S#
AND SC.C# = Course.C#
AND Course.Cname = N'数学'
AND score < 60
--35、查询所有学生的课程及分数情况；
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
ORDER BY Student.S# ,
SC.C#
--36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND SC.score >= 70
ORDER BY Student.S# ,
SC.C#
--37、查询不及格的课程
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND SC.score < 60
ORDER BY Student.S# ,
SC.C#
--38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名；
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND SC.C# = '01'
AND SC.score >= 80
ORDER BY Student.S# ,
SC.C#
--39、求每门课程的学生人数
SELECT Course.C# ,
Course.Cname ,
COUNT(*) [学生人数]
FROM Course ,
SC
WHERE Course.C# = SC.C#
GROUP BY Course.C# ,
Course.Cname
ORDER BY Course.C# ,
Course.Cname
--40、查询选修"张三"老师所授课程的学生中，成绩最高的学生信息及其成绩
--40.1 当最高分只有一个时
SELECT TOP 1
Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course ,
Teacher
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三'
ORDER BY SC.score DESC
--40.2 当最高分出现多个时
SELECT Student.* ,
Course.Cname ,
SC.C# ,
SC.score
FROM Student ,
SC ,
Course ,
Teacher
WHERE Student.S# = SC.S#
AND SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三'
AND SC.score = ( SELECT MAX(SC.score)
FROM SC ,
Course ,
Teacher
WHERE SC.C# = Course.C#
AND Course.T# = Teacher.T#
AND Teacher.Tname = N'张三'
)
--41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
--方法1
SELECT m.*
FROM SC m ,
( SELECT C# ,
score
FROM SC
GROUP BY C# ,
score
HAVING COUNT(1) > 1
) n
WHERE m.C# = n.C#
AND m.score = n.score
ORDER BY m.C# ,
m.score ,
m.S#
--方法2
SELECT m.*
FROM SC m
WHERE EXISTS ( SELECT 1
FROM ( SELECT C# ,
score
FROM SC
GROUP BY C# ,
score
HAVING COUNT(1) > 1
) n
WHERE m.C# = n.C#
AND m.score = n.score )
ORDER BY m.C# ,
m.score ,
m.S#
--42、查询每门功成绩最好的前两名
SELECT t.*
FROM sc t
WHERE score IN ( SELECT TOP 2
score
FROM sc
WHERE C# = T.C#
ORDER BY score DESC )
ORDER BY t.C# ,
t.score DESC
--43、统计每门课程的学生选修人数（超过5人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列
SELECT Course.C# ,
Course.Cname ,
COUNT(*) [学生人数]
FROM Course ,
SC
WHERE Course.C# = SC.C#
GROUP BY Course.C# ,
Course.Cname
HAVING COUNT(*) >= 5
ORDER BY [学生人数] DESC ,
Course.C#
--44、检索至少选修两门课程的学生学号
SELECT student.S# ,
student.Sname
FROM student ,
SC
WHERE student.S# = SC.S#
GROUP BY student.S# ,
student.Sname
HAVING COUNT(1) >= 2
ORDER BY student.S#
--45、查询选修了全部课程的学生信息
--方法1 根据数量来完成
SELECT student.*
FROM student
WHERE S# IN ( SELECT S#
FROM sc
GROUP BY S#
HAVING COUNT(1) = ( SELECT COUNT(1)
FROM course
) )
--方法2 使用双重否定来完成
SELECT t.*
FROM student t
WHERE t.S# NOT IN ( SELECT DISTINCT
m.S#
FROM ( SELECT S# ,
C#
FROM student ,
course
) m
WHERE NOT EXISTS ( SELECT 1
FROM sc n
WHERE n.S# = m.S#
AND n.C# = m.C# ) )
--方法3 使用双重否定来完成
SELECT t.*
FROM student t
WHERE NOT EXISTS ( SELECT 1
FROM ( SELECT DISTINCT
m.S#
FROM ( SELECT S# ,
C#
FROM student ,
course
) m
WHERE NOT EXISTS ( SELECT 1
FROM sc n
WHERE n.S# = m.S#
AND n.C# = m.C# )
) k
WHERE k.S# = t.S# )
--46、查询各学生的年龄
--46.1 只按照年份来算
SELECT * ,
DATEDIFF(yy, sage, GETDATE()) [年龄]
FROM student
--46.2 按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一
SELECT * ,
CASE WHEN RIGHT(CONVERT(VARCHAR(10), GETDATE(), 120), 5) < RIGHT(CONVERT(VARCHAR(10), sage, 120),
5)
THEN DATEDIFF(yy, sage, GETDATE()) - 1
ELSE DATEDIFF(yy, sage, GETDATE())
END [年龄]
FROM student
--47、查询本周过生日的学生
SELECT *
FROM student
WHERE DATEDIFF(week,
DATENAME(yy, GETDATE()) + RIGHT(CONVERT(VARCHAR(10), sage, 120),
6), GETDATE()) = 0
--48、查询下周过生日的学生
SELECT *
FROM student
WHERE DATEDIFF(week,
DATENAME(yy, GETDATE()) + RIGHT(CONVERT(VARCHAR(10), sage, 120),
6), GETDATE()) = -1
--49、查询本月过生日的学生
SELECT *
FROM student
WHERE DATEDIFF(mm,
DATENAME(yy, GETDATE()) + RIGHT(CONVERT(VARCHAR(10), sage, 120),
6), GETDATE()) = 0
--50、查询下月过生日的学生
SELECT *
FROM student
WHERE DATEDIFF(mm,
DATENAME(yy, GETDATE()) + RIGHT(CONVERT(VARCHAR(10), sage, 120),
6), GETDATE()) = -1
DROP TABLE Student,Course,Teacher,SC
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