设有学生--课程数据库包括学生关系Student课程关系Course和选课关系SC。如下图所示 Student学号 Sno姓名 Sname性别 Ssex Sage年龄 Sdept所在系95001 李勇 男 20 CS95002 刘晨 女 19 IS95003 王敏 18 MA女95004 张立 男 19Is课程号 课程名 先行课 学分 Cno Cname Cpno Ccredit 1 数据库 5

CREATE TABLE Student( Sno CHAR(5) PRIMARY KEY, Sname VARCHAR(20), Ssex CHAR(2), Sage INT, Sdept VARCHAR(20) );

CREATE TABLE SC( Sno CHAR(5) REFERENCES Student(Sno), Cno CHAR(5), Grade INT );

INSERT INTO Student(Sno, Sname, Ssex, Sage, Sdept) VALUES('95010', '张三', '男', 22, 'IS');

UPDATE SC SET Grade = Grade * 1.2;

DELETE FROM Student WHERE Sno = '95004';

SELECT Sname, Sdept, Sage FROM Student WHERE Sage NOT BETWEEN 20 AND 23;

SELECT Sno, Sname FROM Student WHERE Sno IN ( SELECT Sno FROM SC WHERE Cno = '2' AND Grade >= 90 );

SELECT * FROM Student WHERE Sdept = 'IS'; -- 可以根据需要进一步处理成图形显