数据库设计的SELECT语句

Question

创建三个基本表，如下：
student(sno,sname,ssex,sage,sdept) 其中sno表示学号,，sname表示姓名，ssex表示性别，sage表示年龄，sdept表示系别。,
course(cno,cname,ccredit,teacher) 其中cno表示课程号，cname表示课程名，ccredit表示课程的学分，teacher表示任课教师。
sc(sno,cno,grade) 其中sno表示学号，cno表示课程号，grade表示学分。
使用SQL语言进行下面的查询：
(1) 查询年龄大于18岁的女生的学号和姓名。
(2) 查询成绩大于85 的学生的学号和姓名。
(3) 查询选修王老师所教授的课程的学生的学号和姓名。

原来都学过,我忘了,哪位高人帮帮在下,谢谢了

Answer 1

SELECT SNO,SNAME FROM STUDENT WHERE SAGE>18

18上面可能要加引号

SELECT SNO,SNAME FROM COURSE WHERE CCREDIT>85

85上面也坑要加引号

SELECT SNO，SNAME FROM STUDENT WHERE STUDENT.SNO=(SELECT SC.SNO FROM SC WHERE CNO=(SELECT CNO FROM COURSE WHERE TEACHER=‘王’））

SELECT SNO,SNAME FROM STUDENT INNER JOIN SC ON SC.SNO=STUDENT.SNO INNER JOIN COURSE ON SC.CNO=COURSE.CNO WHERE COURSE.TEACHER='王‘

Answer 2

1、select sno, sname from student where ssex = '女' and sage > 18
2、select distinct student.sno, student.sname from student inner join sc on student.sno = sc.sno where sc.grade > 85
3、select distinct student.sno, student.sname from student inner join course on student.sno = course.cno where course.teacher like '王%'

Answer 3

sql = "select sno,sname from student where sage>18 and ssex='女'"
sql1= "select sno.cs,sname.dl form sc as cs,student as dl where sno.cs=sno.dl and grade>85"
(3) 查询选修王老师所教授的课程的学生的学号和姓名。此查询由于student表及course表中缺关联字段,无法写出.

Answer 4

select sno,sname from student where sage>18
select student.sno,student.sname from student where course.grade>85 and course.cno=student.cno
select student.sno,student.sname from student where sage>18