1 --1、查询“001”课程比“002”课程成绩高的所有学生的学号；

2 SELECT a.s FROM sc a,sc b WHERE a.s=b.s AND a.c='1' AND b.c='2' AND a.score >b.score;3 --2、查询平均成绩大于60分的同学的学号和平均成绩；

4 SELECT student.s,avg(score) FROM student,sc WHERE student.s=sc.s GROUP BY student.s HAVING avg(score) > 60;5 --3、查询所有同学的学号、姓名、选课数、总成绩；

6 SELECT student.s,sname,COUNT(*),SUM(score) FROM student,course,sc WHERE student.s=sc.s AND course.c=sc.c GROUP BYstudent.s;7 --4、查询姓“李”的老师的个数；

8 SELECT COUNT(*) FROM teacher WHERE tname LIKE '李%';9 --5、检索“004”课程分数小于60，按分数降序排列的同学学号 ；

10 SELECT student.s FROM course,student,sc WHERE course.c = sc.c AND student.s=sc.s AND course.c='4' AND score<60 ORDER BY score DESC;11 --6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；

12 SELECT student.s,sname FROM student,sc a,sc b WHERE a.s=b.s AND student.s=a.s AND student.s=b.s AND a.c='1' AND b.c='2';13 --7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；

14 SELECT student.s,sname FROM student,course,teacher,sc WHERE student.s=sc.s AND course.c=sc.c AND course.t=teacher.t AND tname='叶平';15 --8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名；

16 SELECT student.s,student.sname FROM student,sc a,sc b WHERE student.s=a.s AND student.s=b.s AND a.s=b.s AND a.c='1' AND b.c='2' AND a.score >b.score;17 --9、查询所有课程成绩小于60分的同学的学号、姓名；

18 SELECT s,sname FROM student WHERE s NOT IN (SELECT s FROM sc WHERE score >= 60);19 --10、查询没有学全所有课的同学的学号、姓名；

20 SELECT s,sname FROM student WHERE (SELECT COUNT(*) FROM sc WHERE student.s=sc.s) < (SELECT COUNT(*) FROMcourse);21 --11、查询至少有一门课与学号为“001”的同学所学相同的同学的学号和姓名；

22 SELECT s,sname FROM student WHERE s IN (SELECT DISTINCT s FROM sc WHERE c IN (SELECT c FROM sc WHERE s='1'));23 --12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名；

24 SELECT DISTINCT student.s,sname FROM student,sc WHERE student.s=sc.s AND sc.c IN (SELECT c FROM sc WHERE s='1') AND sc.s != '1';25 --13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩；

26 UPDATE sc SET score=(SELECT e.平均成绩 FROM (SELECT AVG(score) 平均成绩 FROM sc GROUP BY c HAVING c IN

27 (SELECT c FROM course,teacher WHERE course.t=teacher.t AND teacher.tname='叶平'))e);28 --14、查询和“002”号的同学学习的课程完全相同的其他同学学号和姓名；

29 SELECT DISTINCT student.s,sname FROM student,sc WHERE student.s=sc.s AND sc.c IN (SELECT c FROM sc WHERE s='2') AND sc.s != '2';30 --15、删除学习“叶平”老师课的SC表记录；

31 DELETE FROM sc WHERE c=(SELECT e.c FROM (SELECT DISTINCT c FROM sc WHERE c IN

32 (SELECT course.c FROM course,teacher WHERE course.t=teacher.t AND tname='叶平'))e);33 --16、向SC表中插入一些记录，这些记录要求符合以下条件：没有上过编号“003”课程的同学

34 --INSERT表查询结果可以直接将后面的查询结果插入表中

35 INSERT sc SELECT * FROM sc WHERE NOT s IN (SELECT s FROM sc WHERE c=3);36 --17、查询每门课程被选修的学生数

37 SELECT c,COUNT(s) FROM sc GROUP BYc;38 --18、查询出只选修了一门课程的全部学生的学号和姓名

39 SELECT s,sname FROM student WHERE s IN (SELECT s FROM sc GROUP BY s HAVING COUNT(c)=1);40 --19、查询男生、女生人数

41 SELECT COUNT(*) FROM student WHERE ssex='男';42 SELECT COUNT(*) FROM student WHERE ssex='女';43 --20、查询姓“张”的学生名单

44 SELECT * FROM student WHERE sname LIKE '张%';45 --21、查询同名同性学生名单，并统计同名人数

46 SELECT *,COUNT(sname) FROM student GROUP BY sname HAVING COUNT(sname) > 1;47 --22、1981年出生的学生名单(注：Student表中Sage列的类型是datetime)

48 SELECT s,sname FROM student WHERE DATE_FORMAT(saged,'%Y')='1981';49 --23、查询每门课程的平均成绩，结果按平均成绩升序排列，平均成绩相同时，按课程号降序排列

50 SELECT c,AVG(score) FROM sc GROUP BY c ORDER BY AVG(score) ASC,c DESC;51 --24、查询平均成绩大于85的所有学生的学号、姓名和平均成绩

52 SELECT student.s,sname,AVG(score) FROM sc,student WHERE student.s = sc.s GROUP BY student.s HAVING AVG(score) > 85;53 SELECT student.s,student.sname ,e.平均成绩 FROM student,(SELECT s,AVG(score) 平均成绩 FROM sc GROUP BY s HAVING AVG(score)>85) e WHERE student.s=e.s;54 --25、查询课程名称为“数据库”，且分数低于60的学生姓名和分数

55 SELECT sname,score FROM student,course,sc WHERE student.s=sc.s AND course.c=sc.c AND cname='数据库' AND score < 60;56 SELECT student.s ,student.sname ,e.score FROM student,(SELECT s,score FROM sc WHERE c IN (SELECT c FROM course WHERE cname='数据库')AND score<60) e WHERE student.s=e.s;57 --26、查询所有学生的选课情况；

58 SELECT student.s,sname,course.c,cname FROM student,sc,course WHERE course.c=sc.c AND student.s=sc.s;59 --27、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；

60 SELECT sname,cname,score FROM student,course,sc WHERE student.s=sc.s AND course.c=sc.c AND score>70;61 --28、查询不及格的课程，并按课程号从大到小排列

62 SELECT s,score,cname FROM course,sc WHERE course.c=sc.c AND score < 60 GROUP BY course.c ORDER BY course.c DESC;63 --29、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名

64 SELECT student.s,sname FROM student,sc WHERE student.s=sc.s AND c=3 AND score>80;65 --30、求选了课程的学生人数

66 SELECT COUNT(DISTINCT s) FROMsc;67 --32、查询各个课程及相应的选修人数

68 SELECT course.c,cname,COUNT(DISTINCT s) FROM sc,course WHERE sc.c=course.c GROUP BYcourse.c;69 --33、查询不同课程成绩相同的学生的学号、课程号、学生成绩

70 SELECT student.s,course.c,score FROM student,sc,course WHERE student.s=sc.s AND course.c=sc.c71 --34、检索至少选修两门课程的学生学号

72 SELECT DISTINCT s FROM sc GROUP BY c HAVING COUNT(DISTINCTc);73 --35、查询全部学生都选修的课程的课程号和课程名

74 SELECT c,cname FROM course WHERE c IN(SELECT c FROM sc GROUP BYc);75 --36、查询没学过“叶平”老师讲授的任一门课程的学生姓名

76 SELECT sname FROM student WHERE s NOT IN(SELECT s FROM sc,course,teacher WHERE sc.c=course.c AND course.t=teacher.t AND teacher.tname='叶平');77 --37、查询两门以上不及格课程的同学的学号及其平均成绩

78 SELECT s,AVG(IFNULL(score,0)) FROM sc WHERE s IN (SELECT s FROM sc WHERE score<60 GROUP BY s HAVING COUNT(s)>=2 ) GROUP BYs;79 --38、删除“002”同学的“001”课程的成绩

80 DELETE FROM sc WHERE s=2 AND c=1;