复习sql [not] exists

 

DROP TABLE IF EXISTS "test"."course";

CREATE TABLE  "test"."course" (

  "cno" varchar(50) NOT NULL,

  PRIMARY KEY  ("cno")

) ENGINE=InnoDB DEFAULT CHARSET=latin1;//课程表

 

DROP TABLE IF EXISTS "test"."sc";

CREATE TABLE  "test"."sc" (

  "sno" varchar(50) NOT NULL,

  "cno" varchar(45) NOT NULL,

  PRIMARY KEY  ("sno","cno")

) ENGINE=InnoDB DEFAULT CHARSET=latin1;//选课表

 

DROP TABLE IF EXISTS "test"."student";

CREATE TABLE  "test"."student" (

  "sno" varchar(50) NOT NULL,

  PRIMARY KEY  ("sno")

) ENGINE=InnoDB DEFAULT CHARSET=latin1;//学生表

 

//所有 没选择全部课程的学生

select * from student  where exists(select * from course where not exists(

select * from sc where student.sno=sc.sno and course.cno=sc.cno

))

//所有 选择全部课程的学生

select * from student  where not exists(select * from course where not exists(

select * from sc where student.sno=sc.sno and course.cno=sc.cno

))

//...

参考http://wenku.baidu.com/view/567b4a4333687e21af45a93c.html，但是里面的解释有误，故mark在此

但是文章中对于in和exists的适用范围的描述还是比较有说服力的