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3.5 create table student(sno char (9) primary key,sname char(20)unique,ssex char(2),sage smallint,sdept char(20)); 3.6 create table course(cno char(4)primary key,cname char(40)not null,cpno char(4)

 3.35 select * from course where cname like'DB\_%i__'ESCAPE 3.36 select sno,cno from sc where grade is NUll; 3.37 select sno,cno from sc where

 3.50 select student.sno ,sname,ssex,sage,sdept,cno,grade from student,sc where student.sno=sc.sno; 3.51 select sc.sno,sname from sc,student where sc.cno='2' and

例题 ALTER TABLE student ADD s_entrance DATA; ALTER TABLE student ALTER column sage INT; ALTER TABLE course ADD UNIQUE(cname); select sno，sname FROM  student; 3.20 select sname,'year of bir