Mysql使用两个NOT EXISTS表肯定的

原始数据的建表语句：

    create table if not exists student  
    (  
        SNO varchar(20) primary key,  
        SNAME varchar(20) character set gbk,  
        AGE int,  
        SEX  char(2) character set gbk CHECK(SEX IN('男','女'))   
    );  
    insert into student values('1','李强',23,'男');  
    insert into student values('2','刘丽',22,'女');  
    insert into student values('5','张友',22,'男');  
      
    create table if not exists course  
    (  
        CNO varchar(20) primary key,  
        CNAME varchar(20) character set gbk,  
        TEACHER varchar(20) character set gbk  
    );  
    insert into course values('K1','C语言','王华');  
    insert into course values('K5','数据库原理','程军');  
    insert into course values('K8','编译原理','程军');  
      
    create table if not exists sc  
    (  
        SNO varchar(20) NOT NULL,  
        CNO varchar(20) NOT NULL,  
        SCORE int NOT NULL,  
        primary key (SNO,CNO),  
        foreign key (SNO) references student(SNO),  
        foreign key (CNO) references course(CNO)  
    );  
    insert into sc values('1','K1',83);  
    insert into sc values('2','K1',85);  
    insert into sc values('5','K1',92);  
    insert into sc values('2','K5',90);  
    insert into sc values('5','K5',84);  
    insert into sc values('5','K8',80);  

检索至少选修＂程军＂老师所授全部课程的学生姓名（SNAME）；
本题的另外一种说法就是，检索选修了“程军”老师所授全部课程的学生姓名.
本查询可以理解为：查询这样一些学生，没有一门课程是他不选修的。

    select sname from student  
    where not exists  
    (  
       select * from course  
       where teacher='程军' and not exists  
       (  
           select * from sc   
           where sc.sno=student.sno and sc.cno=course.cno  
        )  
    );  

这里的检索结果是：

+-------+
| sname |
+-------+
| 张友  |
+-------+
1 row in set (0.00 sec)

参考：
1、SQL语句大全（包含用两个NOT EXISTS表肯定的SQL语句）：https://blog.csdn.net/qq_41734797/article/details/92803538
2、【MySQL】数据库原理复习——SQL语言：https://www.cnblogs.com/linjiaxin/p/7747944.html