SQL 数据库查询练习：学生-课程数据库操作

(1) 建立 SC 表的 SQL 语句：

CREATE TABLE SC (
    Sno CHAR(10) NOT NULL,
    Cno CHAR(10) NOT NULL,
    Grade FLOAT CHECK (Grade >= 0 AND Grade <= 100),
    PRIMARY KEY (Sno, Cno),
    FOREIGN KEY (Sno) REFERENCES Student(Sno),
    FOREIGN KEY (Cno) REFERENCES Course(Cno)
);

(2) 查询年龄大于 19 岁的'计算机系'的学生学号和姓名的 SQL 语句：

SELECT Sno, Sname
FROM Student
WHERE Sage > 19 AND Sdept = '计算机系';

(3) 将所有女生的成绩加上 10 分的 SQL 语句：

UPDATE SC
SET Grade = Grade + 10
WHERE Sno IN (SELECT Sno FROM Student WHERE Ssex = '女');

(4) 建立视图 E_W 的 SQL 语句：

CREATE VIEW E_W AS
SELECT SC.Sno, Student.Sname, SC.Cno, SC.Grade
FROM SC
JOIN Student ON SC.Sno = Student.Sno
WHERE Student.Sdept = '计算机系';