1.数据建立
Use master
go
if db_id('MySchool') is not null
Drop Database MySchool
Create Database MySchool
go
Use MySchool
go
create table Student
(
S# varchar(5) primary key,
StuName nvarchar(10) not null,
StuAge int,
StuSex nchar(1) not null
)
create table Teacher
(
T# varchar(3) primary key,
Tname varchar(10) not null
)
create table Course
(
C# varchar(3) primary key,
Cname nvarchar(20) not null,
T# varchar(3) not null foreign key references Teacher(T#)
)
create table SC
(
S# varchar(5) not null foreign key references Student(S#),
C# varchar(3) not null foreign key references Course(C#),
Score float
)
go
insert into Student
select '1000','张无忌',18,'男' union
select '1001','周芷若',19,'女' union
select '1002','杨过',19,'男' union
select '1003','赵敏',18,'女' union
select '1004','小龙女',17,'女' union
select '1005','张三丰',18,'男' union
select '1006','令狐冲',19,'男' union
select '1007','任盈盈',20,'女' union
select '1008','岳灵珊',19,'女' union
select '1009','韦小宝',18,'男' union
select '1010','康敏',17,'女' union
select '1011','萧峰',19,'男' union
select '1012','黄蓉',18,'女' union
select '1013','郭靖',19,'男' union
select '1014','周伯通',19,'男' union
select '1015','瑛姑',20,'女' union
select '1016','李秋水',21,'女' union
select '1017','黄药师',18,'男' union
select '1018','李莫愁',18,'女' union
select '1019','冯默风',17,'男' union
select '1020','王重阳',17,'男' union
select '1021','郭襄',18,'女'
go
insert into Teacher
select '001','姚明' union
select '002','叶平' union
select '003','叶开' union
select '004','孟星魂' union
select '005','独孤求败' union
select '006','裘千仞' union
select '007','裘千尺' union
select '008','赵志敬' union
select '009','阿紫' union
select '010','郭芙蓉' union
select '011','佟湘玉' union
select '012','白展堂' union
select '013','吕轻侯' union
select '014','李大嘴' union
select '015','花无缺' union
select '016','金不换' union
select '017','乔丹'
go
insert into Course
select '001','企业管理','002' union
select '002','马克思','008' union
select '003','UML','006' union
select '004','数据库','007' union
select '005','逻辑电路','006' union
select '006','英语','003' union
select '007','电子电路','005' union
select '008','泽东思想概论','004' union
select '009','西方哲学史','012' union
select '010','线性代数','017' union
select '011','计算机基础','013' union
select '012','AUTO CAD制图','015' union
select '013','平面设计','011' union
select '014','Flash动漫','001' union
select '015','Java开发','009' union
select '016','C#基础','002' union
select '017','Oracl数据库原理','010'
go
insert into SC
select '1001','003',90 union
select '1001','002',87 union
select '1001','001',96 union
select '1001','010',85 union
select '1002','003',70 union
select '1002','002',87 union
select '1002','001',42 union
select '1002','010',65 union
select '1003','006',78 union
select '1003','003',70 union
select '1003','005',70 union
select '1003','001',32 union
select '1003','010',85 union
select '1003','011',21 union
select '1004','007',90 union
select '1004','002',87 union
select '1005','001',23 union
select '1006','015',85 union
select '1006','006',46 union
select '1006','003',59 union
select '1006','004',70 union
select '1006','001',99 union
select '1007','011',85 union
select '1007','006',84 union
select '1007','003',72 union
select '1007','002',87 union
select '1008','001',94 union
select '1008','012',85 union
select '1008','006',32 union
select '1009','003',90 union
select '1009','002',82 union
select '1009','001',96 union
select '1009','010',82 union
select '1009','008',92 union
select '1010','003',90 union
select '1010','002',87 union
select '1010','001',96 union
select '1011','009',24 union
select '1011','009',25 union
select '1012','003',30 union
select '1013','002',37 union
select '1013','001',16 union
select '1013','007',55 union
select '1013','006',42 union
select '1013','012',34 union
select '1000','004',16 union
select '1002','004',55 union
select '1004','004',42 union
select '1008','004',34 union
select '1013','016',86 union
select '1013','016',44 union
select '1000','014',75 union
select '1002','016',100 union
select '1004','001',83 union
select '1008','013',97
go
2.查询“001”课程比“002”课程成绩高的所有学生的学号；
你要知道的知识点
distinct是仅选取唯一不同的值。
可以使用关键词 JOIN 来从两个表中获取数据。
在给字段起别名时，可以使用 as ，也可以直接在字段后跟别名，省略 as 。
代码如下
select distinct SC1.S#
from SC SC1 join SC SC2 on SC1.S#=SC2.S#
where SC1.C#='001' and SC2.C#='002' and SC1.Score>SC2.Score
解析
选择学号字段，然后将两个采用笛卡尔积方式连接（并且限制条件为学号相等），这里可以修改distinct SC1.S#为通配符*观察查询效果理解，不多加解释，最后通过where语句来增加限制
