实验内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姓名；SELECT Sno,SnameFROM StudentWHERE Ssex=’男’ANDSage>23;②检索至少选修一门课程的女生姓名；SELECT SnameFROM StudentWHERE Ssex=’女’AND Sno IN( SELECT SnoFROM SCGROUP BY SnoHAVING count(*)>=1;);③检索王同学不学的课程的课程号；SELECT Cno;FROM CourseWHERE Cno NOT IN( SELECT CnoFROM Student,SCWHERE Sname like ’王%’AND Student.Sno=SC.Sno);④检索至少选修两门课程的学生学号；SELECT DISTINCT SnoFROM SCGROUP BY SnoHAVING count(*)>=2;⑤检索全部学生都选修的课程的课程号与课程名；SELECT Cno,CnameFROM CourseWHERE NOT EXISTS( SELECT *FROM StudentWHERE NOT EXISTS( SELECT *FROM SCWHERE SC.Sno=Student.Sno AND o=o));⑥检索选修了所有3学分课程的学生学号；FROM SC XWHERE NOT EXISTS( SELECT *FROM CourseWHERE Ccredit=3 AND NOT EXISTS( SELECT *FROM SC YWHERE X.Sno=Y.Sno AND o=o));（2）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 Cno)FROM SC;②求选修4号课程的学生的平均年龄；SELECT AVG(Sage)FROM Student,SCWHERE Cno=4 AND Student.Sno=SC.Sno;③求学分为3的每门课程的学生平均成绩；SELECT AVG(Grade)FROM Course,SCWHERE Ccredit=3 AND o=oGROUP BY o;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 Cno,count(Sno)FROM SCGROUP BY CnoHAVING count(Sno)>3ORDER BY count(Sno) DESC,Cno ASC;⑤检索学号比“王菲”同学大而年龄比他小的学生姓名；SELECT SnameFROM Student XWHERE Sno>( SELECT SnoFROM Student YWHERE Sname=’王菲’AND Sage>( SELECT SageFROM Student ZWHERE Sname=’王菲’AND X.Sno=Z.Sno AND Y.Sno=Z.Sno));⑥检索姓名以“王”打头的所有学生的姓名和年龄；FROM StudentWHERE Sname LIKE ‘王%’;⑦在SC中检索成绩为空置的学生学号和课程号；SELECT Sno,CnoFROM SCWHERE Grade is NULL;⑧求年龄大于女同学平均年龄的男学生姓名和年龄；SELECT Sname,SageFROM Student XWHERE Ssex=’男’AND Sage>( SELECT AVG(Sage)FROM StudentWHERE Ssex=’女’AND X.Sno=Y.Sno);⑨求年龄大于所有女同学年龄的男同学姓名和年龄；SELECT Sname,SageFROM Student XWHERE Ssex=’男’AND Sage>( SELECT MAX(Sage)FROM Student YWHERE Ssex=’女’AND X.Sno=Y.Sno);⑩检索所有比“王华”年龄大的学生姓名，年龄和性别；SELECT Sname,Sage,SsexFROM Student XWHERE Sage>( SELECT SageFROM Student YWHERE Sname=’王华’AND X.Sno=Y.Sno);①检索选修“2”课程的学生中成绩最高的学生和学号；SELECT Sname,SC.SnoFROM Student,SCWHERE Cno=2 AND Student.Sno=SC.Sno;②检索学生姓名和其所选修课程的课程号和成绩；SELECT Sname,Cno,GradeFROM Student,SCWHERE Student.Sno=SC.SnoGROUP BY Sname;③检索选修4门以上课程的学生总成绩（不统计不及格的课程），并要求按总成绩的降序排列出来；SELECT Sno,SUM(Grade)FROM SC XWHERE Grade>=60 AND Sno IN( SELECT SnoFROM SC YWHERE X.Sno=Y.SnoGROUP BY SnoHAVING count(Cno)>4)` ORDER BY SUM(Grade) DESC;（3）设有表4-1~表4-4的4个基本表（表结构于表内容是假设的），请先创建数据库及根据表内容创建表结构，并添加表记录，写出实现以下各题功能的SQL语句：创建以下4各表：CREATE TABLE STUDENT(SNO CHAR(6) PRIMARY KEY,SNAME CHAR(20) UNIQUE,SEX CHAR(2),AGE SMALLINT,CLASS CHAR(4));CREATE TABLE TEACHER(TNO CHAR(3) PRIMARY KET,TNAMW CHAR(20) UNIQUE,SEX CHAR(2),AGE SMALLINT,PROF CHAR(10),DEPT CHAR(10));CREATE TABLE COURSE(CNO CHAR(4) PRIMARY KEY,CNAME CHAR(20) UNIQUE,TNO CHAT(3),FOREIGN KEY TNO REFERENCES TEACHER(TNO));CREATE TABLE SC(SNO CHAR(6),CNO CHAR(4),GRADE SMALLINT,PRIMARY KEY(SNO,CNO),FOREIGN KEY SNO REFERENCES STUDENT(SNO),FOREIGN KEY CNO REFERENCES COURSE(CNO));插入数据：INSERT INTO STUDENTVALUES(‘980101’,’李华’，‘男’，19，’9801’);......同上方法依次插入数据①查询选修课程“8105”且成绩在80到90之间的所有记录；SELECT *FROM SCWHERE CNO=’8105’AND GRADE BETWEEN 80 AND 90;②查询成绩为79，89或99的记录；SELECT *FROM SCWHERE GRADE IN(79,89,99);③查询“9803”班的学生人数；SELECT count(SNO)FROM STUDENTWHERE SNO LIKE ‘9803%’;④查询至少有20名学生选修的并且课程号以8开头的课程及平均成绩；SELECT CNO,AVG(GRADE)FROM SCWHERE CNO LIKE ‘8%’GROUP BY CNO;HAVING count(SNO)>=20;⑤查询最低分大于80，最高分小于95的SNO与平均分；SELECT SNO,AVG(GRADE)FROM SCGROUP BY SNOHAVING MIN(GRADE)>80 AND MAX(GRADE)<95;⑥查询“9803”班的学生所选各课程的课程号及平均成绩；SELECT CNO,AVG(GRADE)FROM SCWHERE SNO LIKE ‘9803’GROUP BY CNO;⑦查询选修“8105”课程的成绩高于“980302”号同学成绩的所有同学的记录；SELECT *FROM SC XWHERE CNO=’8105’AND GRATE>(SELECT GRATEFROM SC YWHERE CNO=’8105’AND SNO=’980302’AND X.SNO=Y.SNO );⑧查询与学号为“980103”的同学同岁的所有学生的SNO,SNAME和AGE；SELECT SNO,SNAME,AGEFROM STUDENT XWHERE AGE=(SELECT AGEFROM STUDENT YWHERE SNO=’980103’AND X.SNO=Y.SNO);⑨查询“钱军”教师任课的课程号，以及选修其课程学生的学号和成绩；SELECT O,SNO,GRADEFROM SC,TEACHRT,COURSEWHERE TNAME=’钱军’AND TEACHER.TNO=COURSE.TNO AND SC.CON=COURSE.CON;⑩查询选修某课程的学生人数多于20人的教师姓名；SELECT DISTINCT TNAMEFROM TEACHER,SC,COURSEWHERE TEACHER.TNO=COURSE.TNO AND SC.CON=COURSE.CONGROUP BY OHAVING count(SNO)>20;11查询选修编号为“8105”课程且成绩至少高于其选修编号为“8245”课程成绩的同学的SNO及“8105”课程成绩，并按成绩从高到低依次排列；SELECT SNO GRADEFROM SC XWHERE CNO=’8105’AND GRADE>(SELECT GRADEFROM SC YWHERE CNO=’8245’AND X.SNO=Y.SNO)ORDER BY GRADE DESC;12查询选修编号为“8105”课程且成绩高于所有选修编号为“8245”课程成绩的同学的CNO、SNO、GRADE；SELECT CNO,SNO,GRADEFROM SCWHERE CNO=’8105’AND GRADE>(SELECT MAX(GRADE)FROM SCWHERE CNO=’8245’AND O=Y.SNO);13列出所有教师和同学的姓名，SEX,AGE；SELECT TNAME,TEACHER.SEX,TEACHER.AGE,SNAME,STUDENT.SEX,STUDENT.AGEFROM TEACHER,SC14查询成绩比该课程平均成绩高的学生的成绩表；SELECT *FROM SC.XGROUP BY SNOHAVING GRADE>(SELECT AVG(GRADE)FROM SC.YWHERE O=OGROUP BY CNO);15列出所有任课教师的TNAME和DEPT；SELECT TNAME,DEPTFROM TEACHER,COURSEWHERE TEACHER.TNO=COURSE.TNO16列出所有未讲课教师的TNAME和DEPT;SELECT TNAME,DEPYFROM TEACHERWHERE NOT EXISTS(SELECT *FROM COURSEWHERE TEACHER.TNO=COURSE.TNO );17列出至少有4名男生的班号；SELECT CLASSFROM STUDENTGROUP BY CLASSHAVING count(SNO)>=4;18查询不姓“”的学生记录；SELECT *FROM STUDENTWHERE SNAME NOT LIKE ‘%’;19查询每门课最高分的学生的SNO,CNO,GRADE;SELECT SNO,CNO,GRADEFROM SCGROUP BY CNOHAVING GRADE=MAX(GRADE);20查询与“李华”同性并同班的同学SNAME；SELECT SNAMEFROM STUDENT XWHERE CLASS=(SELECT CLASSFROM STUDENT YWHERE SNAME=’李华’AND SEX=(SELSCT SEXFROM STUDENT ZWHERE SNAME=’李华’AND X.SNO=Y.SNO AND Y.SNO=Z.SNO));21查询“女”教师及其所上的课程；SELECT TNAME,CNO,CNAMEFROM TEACHER,COURSEWHERE TEACHER.TNO=COURSE.TNO,SEX=’女’;22查询选修“数据库系统”课程的“男”同学的成绩表；SELECT *FROM SC,COURSE,STUDENTWHERE STUDENT.SNO=SC.SNO AND O=O AND CNAME=’数据库系统’AND SEX=’男’;23查询所有比刘涛年龄大的教师姓名，年龄和刘涛的年龄；SELECT TNAME,AGEFROM TEACHER XWHERE SNAME=’刘涛’OR AGE>(SELECT AGEFROM TEACHER YWHERE X.TNO=Y.TNO AND SNAME=’刘涛’);24查询不讲授“8106”号课程的教师姓名。