mysql基础SQL练习

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表如下：

• Student(Sid,Sname,Sage,Ssex) 学生表
• Course(Cid,Cname,Tid) 课程表
• SC(Sid,Cid,score) 成绩表
• Teacher(Tid,Tname) 教师表

问题：

1、查询“001”课程比“002”课程成绩高的所有学生的学号

select a.Sid from (select sid,score from SC where Cid='001') a,(select sid,score

from SC where Cid='002') b

where a.score>b.score and a.sid=b.sid;

2、查询平均成绩大于60分的同学的学号和平均成绩；

select Sid,avg(score)

from sc

group by Sid having avg(score) >60;

3、查询所有同学的学号、姓名、选课数、总成绩；

select Student.Sid,Student.Sname,count(SC.Cid),sum(score)

from Student left Outer join SC on Student.Sid=SC.Sid

group by Student.Sid,Sname ；

4、查询姓“李”的老师的个数；

select count(distinct(Tname))

from Teacher

where Tname like '李%';

5、查询没学过“叶平”老师课的同学的学号、姓名；

select Student.Sid,Student.Sname

from Student

where Sid not in (select distinct( SC.Sid) from SC,Course,Teacher

where SC.Cid=Course.Cid and Teacher.Tid=Course.Tid and Teacher.Tname='叶平');

6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；

select Student.Sid,Student.Sname from Student,SC

where Student.Sid=SC.Sid and SC.Cid='001'and

exists( Select * from SC as SC_2 where SC_2.Sid=SC.Sid and SC_2.Cid='002');

7、查询学过“叶平”老师所教的所有课的同学的学号、姓名；

select Sid,Sname

from Student

where Sid in (select Sid from SC ,Course ,Teacher

where SC.Cid=Course.Cid and Teacher.Tid=Course.Tid and Teacher.Tname='叶平'

group by Sid having count(SC.Cid)=(select count(Cid) from Course,Teacher

where Teacher.Tid=Course.Tid and Tname='叶平'));

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；

26     Select Sid,Sname from (select Student.Sid,Student.Sname,score ,(select score from SC SC_2

27     where SC_2.Sid=Student.Sid and SC_2.Cid='002') score2

28     from Student,SC where Student.Sid=SC.Sid and Cid='001') S_2 where score2 <score;

9、查询所有课程成绩小于60分的同学的学号、姓名；

29     select Sid,Sname

30     from Student

31     where Sid not in (select Student.Sid from Student,SC where S.Sid=SC.Sid and score>60);

10、查询没有学全所有课的同学的学号、姓名；

32     select Student.Sid,Student.Sname

33     from Student,SC

34     where Student.Sid=SC.Sid

35     group by Student.Sid,Student.Sname having count(Cid) <(select count(Cid) from Course);

11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名；

36     select Sid,Sname from Student,SC

37     where Student.Sid=SC.Sid and Cid in select Cid from SC where Sid='1001';

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；

38     select distinct SC.Sid,Sname

39     from Student,SC

40     where Student.Sid=SC.Sid and Cid in (select Cid from SC where Sid='001');

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；

41     update SC set score=(select avg(SC_2.score)

42     from SC SC_2

43     where SC_2.Cid=SC.Cid ) from Course,Teacher

44     where Course.Cid=SC.Cid and Course.Tid=Teacher.Tid and Teacher.Tname='叶平');

14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名；

45     select Sid from SC where Cid in (select Cid from SC where Sid='1002')

46     group by Sid having count(*)=(select count(*) from SC where Sid='1002');

15、删除学习“叶平”老师课的SC表记录；

47     Delect SC

48     from course ,Teacher

49     where Course.Cid=SC.Cid and Course.Tid= Teacher.Tid and Tname='叶平';

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”课程的同学学号、2、号课的平均成绩；

50     Insert SC select Sid,'002',(Select avg(score)

51     from SC where Cid='002') from Student

52     where Sid not in (Select Sid from SC where Cid='002');

17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩，按如下形式显示： 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分

53     SELECT Sid as 学生ID

54     ,(SELECT score FROM SC WHERE SC.Sid=t.Sid AND Cid='004') AS 数据库

55     ,(SELECT score FROM SC WHERE SC.Sid=t.Sid AND Cid='001') AS 企业管理

56     ,(SELECT score FROM SC WHERE SC.Sid=t.Sid AND Cid='006') AS 英语

57     ,COUNT(*) AS 有效课程数, AVG(t.score) AS 平均成绩

58     FROM SC AS t

59     GROUP BY Sid

60     ORDER BY avg(t.score)

18、查询各科成绩最高和最低的分：以如下形式显示：课程ID，最高分，最低分

61     SELECT L.Cid As 课程ID,L.score AS 最高分,R.score AS 最低分

62     FROM SC L ,SC AS R

63     WHERE L.Cid = R.Cid and

64     L.score = (SELECT MAX(IL.score)

65     FROM SC AS IL,Student AS IM

66     WHERE L.Cid = IL.Cid and IM.Sid=IL.Sid

67     GROUP BY IL.Cid)

68     AND

69     R.Score = (SELECT MIN(IR.score)

70     FROM SC AS IR

71     WHERE R.Cid = IR.Cid

72     GROUP BY IR.Cid

73     );

19、按各科平均成绩从低到高和及格率的百分数从高到低顺序

74     SELECT t.Cid AS 课程号,max(course.Cname)AS 课程名,isnull(AVG(score),0) AS 平均成绩

75     ,100 * SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) AS 及格百分数

76     FROM SC T,Course

77     where t.Cid=course.Cid

78     GROUP BY t.Cid

79     ORDER BY 100 * SUM(CASE WHEN isnull(score,0)>=60 THEN 1 ELSE 0 END)/COUNT(*) DESC

20、查询如下课程平均成绩和及格率的百分数(用"1行"显示): 企业管理（001），马克思（002），OO&UML （003），数据库（004）

80     SELECT SUM(CASE WHEN Cid ='001' THEN score ELSE 0 END)/SUM(CASE Cid WHEN '001' THEN 1 ELSE 0 END) AS 企业管理平均分

81     ,100 * SUM(CASE WHEN Cid = '001' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN Cid = '001' THEN 1 ELSE 0 END) AS 企业管理及格百分数

82     ,SUM(CASE WHEN Cid = '002' THEN score ELSE 0 END)/SUM(CASE Cid WHEN '002' THEN 1 ELSE 0 END) AS 马克思平均分

83     ,100 * SUM(CASE WHEN Cid = '002' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN Cid = '002' THEN 1 ELSE 0 END) AS 马克思及格百分数

84     ,SUM(CASE WHEN Cid = '003' THEN score ELSE 0 END)/SUM(CASE Cid WHEN '003' THEN 1 ELSE 0 END) AS UML平均分

85     ,100 * SUM(CASE WHEN Cid = '003' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN Cid = '003' THEN 1 ELSE 0 END) AS UML及格百分数

86     ,SUM(CASE WHEN Cid = '004' THEN score ELSE 0 END)/SUM(CASE Cid WHEN '004' THEN 1 ELSE 0 END) AS 数据库平均分

87     ,100 * SUM(CASE WHEN Cid = '004' AND score >= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN Cid = '004' THEN 1 ELSE 0 END) AS 数据库及格百分数

88     FROM SC

21、查询不同老师所教不同课程平均分从高到低显示

89     SELECT max(Z.Tid) AS 教师ID,MAX(Z.Tname) AS 教师姓名,C.Cid AS 课程ID,MAX(C.Cname) AS 课程名称,AVG(Score) AS 平均成绩

90     FROM SC AS T,Course AS C ,Teacher AS Z

91     where T.Cid=C.Cid and C.Tid=Z.Tid

92     GROUP BY C.Cid

93     ORDER BY AVG(Score) DESC

22、查询如下课程成绩第 3 名到第 6 名的学生成绩单：企业管理（001），马克思（002），UML （003），数据库（004） [学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩

94     SELECT DISTINCT top 3

95     SC.Sid As 学生学号,

96     Student.Sname AS 学生姓名 ,

97     T1.score AS 企业管理,

98     T2.score AS 马克思,

99     T3.score AS UML,

100   T4.score AS 数据库,

101   ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 总分

102   FROM Student,SC LEFT JOIN SC AS T1

103   ON SC.Sid = T1.Sid AND T1.Cid = '001'

104   LEFT JOIN SC AS T2

105   ON SC.Sid = T2.Sid AND T2.Cid = '002'

106   LEFT JOIN SC AS T3

107   ON SC.Sid = T3.Sid AND T3.Cid = '003'

108   LEFT JOIN SC AS T4

109   ON SC.Sid = T4.Sid AND T4.Cid = '004'

110   WHERE student.Sid=SC.Sid and

111   ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)

112   NOT IN

113   (SELECT

114   DISTINCT

115   TOP 15 WITH TIES

116   ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)

117   FROM sc

118   LEFT JOIN sc AS T1

119   ON sc.Sid = T1.Sid AND T1.Cid = 'k1'

120   LEFT JOIN sc AS T2

121   ON sc.Sid = T2.Sid AND T2.Cid = 'k2'

122   LEFT JOIN sc AS T3

123   ON sc.Sid = T3.Sid AND T3.Cid = 'k3'

124   LEFT JOIN sc AS T4

125   ON sc.Sid = T4.Sid AND T4.Cid = 'k4'

126   ORDER BY ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) DESC);

23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ <60]

127   SELECT SC.Cid as 课程ID, Cname as 课程名称

128   ,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85]

129   ,SUM(CASE WHEN score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70]

130   ,SUM(CASE WHEN score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60]

131   ,SUM(CASE WHEN score < 60 THEN 1 ELSE 0 END) AS [60 -]

132   FROM SC,Course

133   where SC.Cid=Course.Cid

134   GROUP BY SC.Cid,Cname;

24、查询学生平均成绩及其名次

135   SELECT 1+(SELECT COUNT( distinct 平均成绩)

136   FROM (SELECT Sid,AVG(score) AS 平均成绩

137   FROM SC

138   GROUP BY Sid

139   ) AS T1

140   WHERE 平均成绩 > T2.平均成绩) as 名次,

141   Sid as 学生学号,平均成绩

142   FROM (SELECT Sid,AVG(score) 平均成绩

143   FROM SC

144   GROUP BY Sid

145   ) AS T2

146   ORDER BY 平均成绩 desc;

25、查询各科成绩前三名的记录:(不考虑成绩并列情况)

147   SELECT t1.Sid as 学生ID,t1.Cid as 课程ID,Score as 分数

148   FROM SC t1

149   WHERE score IN (SELECT TOP 3 score

150   FROM SC

151   WHERE t1.Cid= Cid

152   ORDER BY score DESC

153   )

154   ORDER BY t1.Cid;

26、查询每门课程被选修的学生数

155   select cid,count(Sid) from sc group by Cid;

27、查询出只选修了一门课程的全部学生的学号和姓名

156   select SC.Sid,Student.Sname,count(Cid) AS 选课数

157   from SC ,Student

158   where SC.Sid=Student.Sid group by SC.Sid ,Student.Sname having count(Cid)=1;

28、查询男生、女生人数

159   Select count(Ssex) as 男生人数 from Student group by Ssex having Ssex='男';

160   Select count(Ssex) as 女生人数 from Student group by Ssex having Ssex='女'；

29、查询姓“张”的学生名单

161   SELECT Sname FROM Student WHERE Sname like '张%';

30、查询同名同性学生名单，并统计同名人数

162   select Sname,count(*) from Student group by Sname having count(*)>1;;

31、1981年出生的学生名单(注：Student表中Sage列的类型是datetime)

163   select Sname, CONVERT(char (11),DATEPART(year,Sage)) as age

164   from student

165   where CONVERT(char(11),DATEPART(year,Sage))='1981';

32、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

166   Select Cid,Avg(score) from SC group by Cid order by Avg(score),Cid DESC ;

33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩

167   select Sname,SC.Sid ,avg(score)

168   from Student,SC

169   where Student.Sid=SC.Sid group by SC.Sid,Sname having avg(score)>85;

34、查询课程名称为“数据库”，且分数低于60的学生姓名和分数

170   Select Sname,isnull(score,0)

171   from Student,SC,Course

172   where SC.Sid=Student.Sid and SC.Cid=Course.Cid and Course.Cname='数据库'and score <60;

35、查询所有学生的选课情况；

173   SELECT SC.Sid,SC.Cid,Sname,Cname

174   FROM SC,Student,Course

175   where SC.Sid=Student.Sid and SC.Cid=Course.Cid ;

36、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；

176   SELECT distinct student.Sid,student.Sname,SC.Cid,SC.score

177   FROM student,Sc

178   WHERE SC.score>=70 AND SC.Sid=student.Sid;

37、查询不及格的课程，并按课程号从大到小排列

179   select cid from sc where scor e <60 order by Cid ;

38、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；

180   select SC.Sid,Student.Sname from SC,Student

181   where SC.Sid=Student.Sid and Score>80 and Cid='003';

39、求选了课程的学生人数

182   select count(*) from sc;

40、查询选修“叶平”老师所授课程的学生中，成绩最高的学生姓名及其成绩

183   select Student.Sname,score

184   from Student,SC,Course C,Teacher

185   where Student.Sid=SC.Sid and SC.Cid=C.Cid and C.Tid=Teacher.Tid and Teacher.Tname='叶平'

186   and SC.score=(select max(score)from SC where Cid=C.Cid );

41、查询各个课程及相应的选修人数

187   select count(*) from sc group by Cid;

42、查询不同课程成绩相同的学生的学号、课程号、学生成绩

188   select distinct A.Sid,B.score from SC A ,SC B where A.Score=B.Score and A.Cid <>B.Cid ;

43、查询每门功成绩最好的前两名

189   SELECT t1.Sid as 学生ID,t1.Cid as 课程ID,Score as 分数

190   FROM SC t1

191   WHERE score IN (SELECT TOP 2 score

192   FROM SC

193   WHERE t1.Cid= Cid

194   ORDER BY score DESC

195   )

196   ORDER BY t1.Cid;

44、统计每门课程的学生选修人数（超过10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，查询结果按人数降序排列，若人数相同，按课程号升序排列

197   select Cid as 课程号,count(*) as 人数

198   from sc

199   group by Cid

200   order by count(*) desc,cid

45、检索至少选修两门课程的学生学号

201   select Sid

202   from sc

203   group by sid

204   having count(*) > = 2

46、查询全部学生都选修的课程的课程号和课程名

205   select Cid,Cname

206   from Course

207   where Cid in (select cid from sc group by cid)

47、查询没学过“叶平”老师讲授的任一门课程的学生姓名

208   select Sname from Student where Sid not in (select Sid from Course,Teacher,SC

209   where Course.Tid=Teacher.Tid and SC.Cid=course.Cid and Tname='叶平');

48、查询两门以上不及格课程的同学的学号及其平均成绩

210   select Sid,avg(isnull(score,0)) from SC

211   where Sid in (select Sid from SC where score <60

212   group by Sid having count(*)>2)group by Sid;

49、检索“004”课程分数小于60，按分数降序排列的同学学号

213   select Sid from SC where Cid='004'and score <60 order by score desc;

50、删除“002”同学的“001”课程的成绩

214   delete from Sc where Sid='001'and Cid='001';