1、create table student(sno smallint constraint a primary key,-设置学生学号为student的主键sname varchar(10) not null,sex varchar(2) constraint b check(sex in(男,女),-检查约束性别的值只能是男或女dept varchar(20) constraint c check(dept in(信息系计算机科学系数学系管理系中文系外语系法学系),-检查约束系包括这几个:birth datetime,age smallint constraint d check(age be
2、tween 0 and 100)-检查约束年龄为数值型,且在100之间)cs(成绩表):cnocj(1)sno和cno分别参照student和course表中的sno,cno的字段(2)cj(成绩)只能在0100之间,可以不输入值create table cs(sno smallint not null references student(sno),-定义成外键cno smallint not null references course(cno),-定义成外键cj smallint constraint e check(cj between 0 and 100),-检查约束cj(成绩)只能
3、在100之间,可以不输入值constraint f primary key(sno,cno)-定义学生学号和课程号为sc表的主键course(课程表)cname其约束如下:(1)课程号(cno)不能有重复的(2)课程名(cname)非空create table course(cno smallint not null constraint g primary key,-设置课程号为course的主键cname varchar(20) not null(三)针对学生课程数据库查询(1) 查询全体学生的学号与姓名。Select sno,sname from student(2) 查询全体学生的姓名
4、、学号、所在系,并用别名显示出结果。Select sname as 姓名,sno as 学号,dept as 所在地 from student(3) 查询全体学生的详细记录。select * from student(4) 查全体学生的姓名及其出生年份。select sname,birth from student (5) 查询学校中有哪些系。select distinct dept from student(6) 查询选修了课程的学生学号。select sno from cs where cno is not null(7) 查询所有年龄在20岁以下的学生姓名及其年龄。select snam
5、e,age from student where age 20(8) 查询年龄在2023岁(包括20岁和23岁)之间的学生的姓名、系别和年龄。select sname,dept,age from student where age between 20 and 23(9) 查询年龄不在2023岁之间的学生姓名、系别和年龄。select sname,dept,age from student where age23(10) 查询信息系、数学系和计算机科学系生的姓名和性别。select sname,sex from student where dept= or dept=(11) 查询既不是信息系
6、、数学系,也不是计算机科学系的学生的姓名和性别。select sname,sex from student where dept!= and dept!(12) 查询所有姓刘学生的姓名、学号和性别。select sname,sno,sex from student where sname like(刘%(13) 查询学号为2009011的学生的详细情况。(具体的学号值根据表中数据确定)select * from student where sno=5(14) 查询姓“欧阳”且全名为三个汉字的学生姓名select sname from student where sname like(欧阳_(1
7、5) 查询名字中第2个字为“晨”字的学生的姓名和学号select sname,sno from student where sname like(_晨(16) 查询所有不姓刘的学生姓名。select sname,sno from student where sname not like(17) 查询sql课程的课程号和学分。select cno from course where cname=sql(18) 查询以DB_开头,且倒数第3个字符为 i的课程的详细情况。select * from course where cname like(DB_%i_(19) 查询缺少成绩的学生的学号和相应的
8、课程号。select sno,cno from cs where cj is null(20) 查所有有成绩的学生学号和课程号。select sno,cno from cs where cj is not null(21) 查询计算机系年龄在20岁以下的学生姓名。select sname from student where age 3(32) 查询有3门以上课程是90分以上的学生的学号及(90分以上的)课程数。select sno, count(cno) as 课程数 from cs where cj90 group by sno having count(cno)=3(33) 查询学生20
9、06011选修课程的总学分。select sum(course) from course,cs where o=cs.sno and cs.sno=2006011(34) 查询每个学生选修课程的总学分。select sno,sum(cj)from cs,coursewhere o=ogroup by snounionselect sno, 0 from studentwhere sno not in (select sno from cs) (35) 查询每个学生及其选修课程的情况。select cs.sno,course.* from cs,course where o=o (36) 查询选
10、修2号课程且成绩在90分以上的所有学生的学号、姓名select sno,sname from student where sno=(select sno from cs where cno=2 and cj90)(37) 查询每个学生的学号、姓名、选修的课程名及成绩。select student.sno,sname,course.course,cs.cj from student,course,cs where student.sno=cs.sno and o=o(38) 查询与“刘晨”在同一个系学习的学生(分别用嵌套查询和连接查询)-嵌套查询select * from student where dept in(select dept from student where sname=刘晨-连接查询select stu1.* from student as stu1,student as stu2 where stu1.dept=stu2.dept and stu2.sname=-exists查询select * from student s1 where exists(select * from student s2 where s1.dept=s2.dept ands2.sname= (39) 查询选修了课程名
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