--SQL测试题:查询每门课,女生成绩比男生成绩好的学生
--sid 学号
--sname 学生姓名
--sex 性别 f女 m男
--cid 课程编码
--grade 成绩
create table student(sid varchar(100), sname varchar(100), sex varchar(1));
create table sc(sid varchar(100), cid varchar(100), grade int);
insert into student(sid, sname, sex) values ('f1', '', 'f');
insert into student(sid, sname, sex) values ('f2', '', 'f');
insert into student(sid, sname, sex) values ('f3', '', 'f');
insert into student(sid, sname, sex) values ('f4', '', 'f');
insert into student(sid, sname, sex) values ('f5', '', 'f');
insert into student(sid, sname, sex) values ('f6', '', 'f');
insert into student(sid, sname, sex) values ('f7', '', 'f');
insert into student(sid, sname, sex) values ('m1', '', 'm');
insert into student(sid, sname, sex) values ('m2', '', 'm');
insert into student(sid, sname, sex) values ('m3', '', 'm');
insert into student(sid, sname, sex) values ('m4', '', 'm');
insert into student(sid, sname, sex) values ('m5', '', 'm');
insert into student(sid, sname, sex) values ('m6', '', 'm');
insert into student(sid, sname, sex) values ('m7', '', 'm');
insert into sc(sid, cid, grade) values ('f1', 'c1', 100);
insert into sc(sid, cid, grade) values ('f2', 'c1', 90);
insert into sc(sid, cid, grade) values ('f3', 'c1', 89);
insert into sc(sid, cid, grade) values ('f4', 'c1', 70);
insert into sc(sid, cid, grade) values ('f5', 'c1', 60);
insert into sc(sid, cid, grade) values ('f6', 'c1', 50);
insert into sc(sid, cid, grade) values ('f7', 'c1', 40);
insert into sc(sid, cid, grade) values ('m1', 'c1', 99);
insert into sc(sid, cid, grade) values ('m2', 'c1', 89);
insert into sc(sid, cid, grade) values ('m3', 'c1', 79);
insert into sc(sid, cid, grade) values ('m4', 'c1', 69);
insert into sc(sid, cid, grade) values ('m5', 'c1', 59);
insert into sc(sid, cid, grade) values ('m6', 'c1', 49);
insert into sc(sid, cid, grade) values ('m7', 'c1', 39);
insert into sc(sid, cid, grade) values ('f1', 'c2', 100);
insert into sc(sid, cid, grade) values ('f2', 'c2', 90);
insert into sc(sid, cid, grade) values ('f3', 'c2', 89);
insert into sc(sid, cid, grade) values ('f4', 'c2', 70);
insert into sc(sid, cid, grade) values ('f5', 'c2', 60);
insert into sc(sid, cid, grade) values ('f6', 'c2', 50);
insert into sc(sid, cid, grade) values ('f7', 'c2', 40);
insert into sc(sid, cid, grade) values ('m1', 'c2', 99);
insert into sc(sid, cid, grade) values ('m2', 'c2', 89);
insert into sc(sid, cid, grade) values ('m3', 'c2', 79);
insert into sc(sid, cid, grade) values ('m4', 'c2', 69);
insert into sc(sid, cid, grade) values ('m5', 'c2', 59);
insert into sc(sid, cid, grade) values ('m6', 'c2', 49);
insert into sc(sid, cid, grade) values ('m7', 'c2', 39);
求简单SQL语句