个项目涉及到的50个Sql语句(整理版)
时间：2021-07-01 10:21:17
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标题：一个项目涉及到的50个Sql语句(整理版)
作者：爱新觉罗.毓华(十八年风雨，守得冰山雪莲花开)
时间：2010-05-10
地点：重庆航天职业学院
说明：以下五十个语句都按照测试数据进行过测试，最好每次只单独运行一个语句。
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
createtable Student(S# varchar(10),Sname nvarchar(10),Sage datetime,Ssex nvarchar(10))
insertinto Student values(‘01‘ , N‘赵雷‘ , ‘1990-01-01‘ , N‘男‘)
insertinto Student values(‘02‘ , N‘钱电‘ , ‘1990-12-21‘ , N‘男‘)
insertinto Student values(‘03‘ , N‘孙风‘ , ‘1990-05-20‘ , N‘男‘)
insertinto Student values(‘04‘ , N‘李云‘ , ‘1990-08-06‘ , N‘男‘)
insertinto Student values(‘05‘ , N‘周梅‘ , ‘1991-12-01‘ , N‘女‘)
insertinto Student values(‘06‘ , N‘吴兰‘ , ‘1992-03-01‘ , N‘女‘)
insertinto Student values(‘07‘ , N‘郑竹‘ , ‘1989-07-01‘ , N‘女‘)
insertinto Student values(‘08‘ , N‘王菊‘ , ‘1990-01-20‘ , N‘女‘)
createtable Course(C# varchar(10),Cname nvarchar(10),T# varchar(10))
insertinto Course values(‘01‘ , N‘语文‘ , ‘02‘)
insertinto Course values(‘02‘ , N‘数学‘ , ‘01‘)
insertinto Course values(‘03‘ , N‘英语‘ , ‘03‘)
createtable Teacher(T# varchar(10),Tname nvarchar(10))
insertinto Teacher values(‘01‘ , N‘张三‘)
insertinto Teacher values(‘02‘ , N‘李四‘)
insertinto Teacher values(‘03‘ , N‘王五‘)
createtable SC(S# varchar(10),C# varchar(10),score decimal(18,1))
insertinto SC values(‘01‘ , ‘01‘ , 80)
insertinto SC values(‘01‘ , ‘02‘ , 90)
insertinto SC values(‘01‘ , ‘03‘ , 99)
insertinto SC values(‘02‘ , ‘01‘ , 70)
insertinto SC values(‘02‘ , ‘02‘ , 60)
insertinto SC values(‘02‘ , ‘03‘ , 80)
insertinto SC values(‘03‘ , ‘01‘ , 80)
insertinto SC values(‘03‘ , ‘02‘ , 80)
insertinto SC values(‘03‘ , ‘03‘ , 80)
insertinto SC values(‘04‘ , ‘01‘ , 50)
insertinto SC values(‘04‘ , ‘02‘ , 30)
insertinto SC values(‘04‘ , ‘03‘ , 20)
insertinto SC values(‘05‘ , ‘01‘ , 76)
insertinto SC values(‘05‘ , ‘02‘ , 87)
insertinto SC values(‘06‘ , ‘01‘ , 31)
insertinto SC values(‘06‘ , ‘03‘ , 34)
insertinto SC values(‘07‘ , ‘02‘ , 89)
insertinto 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
leftjoin SC b on a.S# = b.S# and b.C# =‘01‘
leftjoin 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
leftjoin SC b on a.S# = b.S# and b.C# =‘01‘
leftjoin SC c on a.S# = c.S# and c.C# =‘02‘
whereisnull(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) asdecimal(18,2)) avg_score
from Student a , sc b
where a.S# = b.S#
groupby a.S# , a.Sname
havingcast(avg(b.score) asdecimal(18,2)) >=60
orderby 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) asdecimal(18,2)) avg_score
from Student a , sc b
where a.S# = b.S#
groupby a.S# , a.Sname
havingcast(avg(b.score) asdecimal(18,2)) <60
orderby 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) asdecimal(18,2)),0) avg_score
from Student a leftjoin sc b
on a.S# = b.S#
groupby a.S# , a.Sname
havingisnull(cast(avg(b.score) asdecimal(18,2)),0) <60
orderby 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#
groupby a.S#,a.Sname
orderby 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 leftjoin SC b
on a.S# = b.S#
groupby a.S#,a.Sname
orderby a.S#
--6、查询"李"姓老师的数量
--方法1
selectcount(Tname) ["李"姓老师的数量]from Teacher where Tname like N‘李%‘
--方法2
selectcount(Tname) ["李"姓老师的数量]from Teacher whereleft(Tname,1) = N‘李‘
/*
"李"姓老师的数量
-----------
1
*/
--7、查询学过"张三"老师授课的同学的信息
selectdistinct 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‘
orderby 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# notin (selectdistinct SC.S# from SC , Course , Teacher where SC.C# = Course.C# and Course.T# = Teacher.T# and Teacher.Tname = N‘张三‘) orderby 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‘andexists (Select1from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# =‘02‘) orderby Student.S#
--方法2
select Student.*from Student , SC where Student.S# = SC.S# and SC.C# =‘02‘andexists (Select1from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# =‘01‘) orderby Student.S#
--方法3
select m.*from Student m where S# in
(
select S# from
(
selectdistinct S# from SC where C# =‘01‘
unionall
selectdistinct S# from SC where C# =‘02‘
) t groupby S# havingcount(1) =2
)
orderby 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‘andnotexists (Select1from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# =‘02‘) orderby Student.S#
--方法2
select Student.*from Student , SC where Student.S# = SC.S# and SC.C# =‘01‘and Student.S# notin (Select SC_2.S# from SC SC_2 where SC_2.S# = SC.S# and SC_2.C# =‘02‘) orderby 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#
groupby Student.S# , Student.Sname , Student.Sage , Student.Ssex havingcount(C#) < (selectcount(C#) from Course)
--11.2
select Student.*
from Student leftjoin SC
on Student.S# = SC.S#
groupby Student.S# , Student.Sname , Student.Sage , Student.Ssex havingcount(C#) < (selectcount(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
selectdistinct 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
(selectdistinct SC.S# from SC where S# <>‘01‘and SC.C# in (selectdistinct C# from SC where S# =‘01‘)
groupby SC.S# havingcount(1) = (selectcount(1) from SC where S#=‘
