WebJun 3, 2024 · SELECT Sname FROM Student WHERE NOT EXISTS ( SELECT * FROM SC WHERE Sno=Student.Sno AND Cno='1'); 或 SELECT Sname FROM Student WHERE Sno NOT IN (SELECT Sno FROM SC WHERE Cno='1'); 但如下是错的: SELECT Sname FROM Student,SC WHERE SC.Sno=Student.Sno AND Cno>'1'; [例20] 查询选修了全部 … Webprimary key(sno,cno) foreign key(sno) references students(sno) foreign key(cno) references courses(cno) check ((grade is null) or (grade between 0 and 100))) 例 3 根据表的 students 表,建立一个只包含学号、姓名、年龄的女学生表。 create table girl . as select sno, sname, age . from students . where sex=' 女 ';
数据库作业13:SQL练习8 – CHECK / CONSTRAINT / TRIGGER / …
WebMySQL:. 说明:要先创建Student表和Course表. create table SC (Sno varchar (7),Cno varchar (10),Grade int check (Grade >=0 and Grade <=100),primary key (Sno,Cno),foreign key (Sno) references Student … WebMySQL 外键约束(FOREIGN KEY) 是表的一个特殊字段,经常与主键约束一起使用。. 对于两个具有关联关系的表而言,相关联字段中主键所在的表就是主表(父表),外键所在的表就是从表(子表)。. 外键用来建立主表与从表的关联关系,为两个表的数据建立连接 ... onan rocker switch
SQL server学习笔记(一) - 知乎 - 知乎专栏
Web使用自然连结的写法 select course.Cname ,avg (sc.Grade) from course natural join sc group by sc.Cno; 4)查询任何学生后,修改其姓名,然后再显示; 主键查询学生 select Sno,Sname,Ssex,Sage,Sdept from student where Sno = (id) 修改学生的姓名 update student set Sname= (sname) where Sno = id 显示学生 return ... WebCREATE TABLE SC (Sno CHAR (9) NOT NULL, Cno CHAR (4) NOT NULL, Grade SMALLINT, PRIMARY KEY (Sno, Cno), /*在表级定义实体完整性,Sno,Cno 都不能取空值*/ FOREIGN KEY (Sno) REFERENCES Student (Sno) /*在表级定义参照完整性*/ ON DELETE CASCADE /*级联删除SC表中相应的元组*/ ON UPDATE CASCADE, /*级联更 … WebNov 9, 2009 · primary key (Sno,Cno), foreign key (sno) references student (Sno), 后面是foreign key(Cno)references Course (cno)吗?. SNO好像对的,Cno的长度应该是10. … onan road