文档介绍：实验容与要求
请有选择地实践以下各题。
（1）基于“教学管理”数据库jxgl，使用SQL的查询语句表达下列查询：
①检索年龄大于23岁的男学生的学号和；
SELECT Sno,Sname
FROM Student
WHERE Ssex=’男’AND
Sage>23;
②检索至少选修一门课程的女生；
SELECT Sname
FROM Student
WHERE Ssex=’女’AND Sno IN
( SELECT Sno
FROM SC
GROUP BY Sno
HAVING count(*)>=1;
);
③检索王同学不学的课程的课程号；
SELECT o;
FROM Course
WHERE o NOT IN
( SELECT o
FROM Student,SC
WHERE Sname like ’王%’AND =
);
④检索至少选修两门课程的学生学号；
SELECT DISTINCT Sno
FROM SC
GROUP BY Sno
HAVING count(*)>=2;
⑤检索全部学生都选修的课程的课程号与课程名；
SELECT o,ame
FROM Course
WHERE NOT EXISTS
( SELECT *
FROM Student
WHERE NOT EXISTS
( SELECT *
FROM SC
WHERE = AND =
)
);
⑥检索选修了所有3学分课程的学生学号；
SELECT DISTINCT Sno
FROM SC X
WHERE NOT EXISTS
( SELECT *
FROM Course
WHERE Ccredit=3 AND NOT EXISTS
( SELECT *
FROM SC Y
WHERE = AND =
)
);
基于“教学管理”数据库jxgl，使用SQL的查询语句表达下列查询：
①统计有学生选修的课程门数；
SELECT count(DISTINCT o)
FROM SC;
②求选修4号课程的学生的平均年龄；
SELECT AVG(Sage)
FROM Student,SC
WHERE o=4 AND =;
③求学分为3的每门课程的学生平均成绩；
SELECT AVG(Grade)
FROM Course,SC
WHERE Ccredit=3 AND =
GROUP BY ;
④统计每门课程的学生选修人数，要求超过3人的课程才统计，要求输出课程号和选修人数,查询结果按人数降序排列，若人数相同，按课程号升序排列；
SELECT o,count(Sno)
FROM SC
GROUP BY o
HAVING count(Sno)>3
ORDER BY count(Sno) DESC,o ASC;
⑤检索学号比“王菲”同学大而年龄比他小的学生；
SELECT Sname
FROM Student X
WHERE Sno>
(