andStudent.s_no=Choice.s_no
（3）selectStudent.s_no,s_name,Choice.course_no,course_name,score fromclass,Student,Choice,Course
whereclass_name='计算机99-1'andChoice.course_no=Course.course_noand Choice.s_no=Student.s_no
（4）selectStudent.s_no,s_name,sum(course_score)astotal_score
FromStudent
InnerjoinChoiceonStudent.s_no=Choice.s_no
InnerjoinCourseonChoice.course_no=Course.course_noandscore>=60 groupbyStudent.s_no,s_name
（5）selectc.s_no,s.s_name,avg(c.score)average_score,count(*)choice_num
fromChoicec,Studentswherec.s_no=s.s_nogroupbyc.s_no,s.s_name;
(6) selects.s_no,s.s_name,co.course_no,co.course_namefromChoicec,Students,Courseco
wherec.score=0 andc.s_no=s.s_noandco.course_no=c.course_no;
(7) selectst.s_no,st.s_name,co.course_no,co.course_name,co.course_score
fromChoicec,Courseco,Studentst
wherec.score<60 andc.s_no=st.s_noandco.course_no=c.course_no;
(8) selectst.s_name,c.scorefromChoicec,Courseco,Studentstwhere
st.s_no=c.s_noandco.course_no=c.course_noandco.course_name='程序设计语言';
(9) selectst.s_no,st.s_name,c.class_name,co.course_no,co.course_name,ch.score fromStudentst,Classc,Choicech,Courseco
Wherec.class_no=st.class_noandc.class_dept='计算机系'andch.s_no=st.s_noandco.course_no=ch.course_no;
(10) selectte.t_name,co.course_namefromTeachingt,Teacherte,Courseco
wheret.t_no=te.t_noandco.course_no=t.couse_no;
(11)selectt.t_no,te.t_name,count(*)course_number
fromTeachingt,Teacherte wheret.t_no=te.t_no groupbyt.t_no,te.t_name;
(12)select*fromStudentst
wherest.class_noin(selectclass_nofromStudentwheres_name='李建国')
(13)select*fromChoicech,Studentst
wherenotExists(selectcourse_nofromCoursewherecourse_name='计算机基础'andch.course_no!=course_no) andst.s_no=ch.s_no;