建立 SCT 数据库

/* 创建学生表并添加数据*/ create table Student( Sno char(9) primary key, Sname nvarchar(40) not null, Ssex char(2) default ('男'), Sage smallint, Sdept nvarchar(20), ); insert into Student values ('201215121', '李勇', '男', 20, 'CS'); insert into Student values ('201215122', '刘晨', '女', 19, 'CS'); insert into Student values ('201215123', '王敏', '女', 18, 'MA'); insert into Student values ('201215125', '张立', '男', 19, 'IS'); /* 创建课程表并添加数据*/ create table Course ( Cno char(4) not null, Cname char(40) not null, Cpno char(4) , Credit smallint check (Credit >= 0), primary key(Cno), foreign key (Cpno) references Course(Cno) );insert into Course(Cno, Cname, Credit) values('1', '数据库', 4); insert into Course(Cno, Cname, Credit) values('2', '数学', 2); insert into Course(Cno, Cname, Credit) values('3', '信息系统', 4); insert into Course(Cno, Cname, Credit) values('4', '操作系统', 3); insert into Course(Cno, Cname, Credit) values('5', '数据结构', 4); insert into Course(Cno, Cname, Credit) values('6', '数据处理', 2); insert into Course(Cno, Cname, Credit) values('7', 'PASCAL语言', 4);update Course set Cpno = 5 where Cno = 1; update Course set Cpno = 1 where Cno = 3; update Course set Cpno = 6 where Cno = 4; update Course set Cpno = 7 where Cno = 5; update Course set Cpno = 6 where Cno = 7;/* 创建成绩表并添加数据*/ create table SC( Sno char(9), Cno char(4), Grade int check(Grade >= 0 and Grade < 100), primary key (Sno , Cno), foreign key (Sno) references Student(Sno), foreign key (Cno) references Course(Cno) );insert into SC values('201215121', '1', 92); insert into SC values('201215121', '2', 85); insert into SC values('201215121', '3', 88); insert into SC values('201215122', '2', 90); insert into SC values('201215122', '3', 80);

数据库实验

/* 单表查询2*/ select Sname from Student where Sage < 20; select Sno, avg(Grade) from SC group by Sno; select * into gileStudent from Student where Ssex = '女'; /* 连接查询*/

总结

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