1 SET NAMES utf8;
2 SET FOREIGN_KEY_CHECKS = 0;
3
4 -- ----------------------------
5 -- Table structure for `class`
6 -- ----------------------------
7 DROP TABLE IF EXISTS `class`;
8 CREATE TABLE `class` (
9 `cid` int(11) NOT NULL AUTO_INCREMENT,
10 `caption` varchar(32) NOT NULL,
11 PRIMARY KEY (`cid`)
12 ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
13
14 -- ----------------------------
15 -- Records of `class`
16 -- ----------------------------
17 BEGIN;
18 INSERT INTO `class` VALUES ('1', '三年二班'), ('2', '三年三班'), ('3', '一年二班'), ('4', '二年九班');
19 COMMIT;
20
21 -- ----------------------------
22 -- Table structure for `course`
23 -- ----------------------------
24 DROP TABLE IF EXISTS `course`;
25 CREATE TABLE `course` (
26 `cid` int(11) NOT NULL AUTO_INCREMENT,
27 `cname` varchar(32) NOT NULL,
28 `teacher_id` int(11) NOT NULL,
29 PRIMARY KEY (`cid`),
30 KEY `fk_course_teacher` (`teacher_id`),
31 CONSTRAINT `fk_course_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teacher` (`tid`)
32 ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
33
34 -- ----------------------------
35 -- Records of `course`
36 -- ----------------------------
37 BEGIN;
38 INSERT INTO `course` VALUES ('1', '生物', '1'), ('2', '物理', '2'), ('3', '体育', '3'), ('4', '美术', '2');
39 COMMIT;
40
41 -- ----------------------------
42 -- Table structure for `score`
43 -- ----------------------------
44 DROP TABLE IF EXISTS `score`;
45 CREATE TABLE `score` (
46 `sid` int(11) NOT NULL AUTO_INCREMENT,
47 `student_id` int(11) NOT NULL,
48 `course_id` int(11) NOT NULL,
49 `num` int(11) NOT NULL,
50 PRIMARY KEY (`sid`),
51 KEY `fk_score_student` (`student_id`),
52 KEY `fk_score_course` (`course_id`),
53 CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`),
54 CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`)
55 ) ENGINE=InnoDB AUTO_INCREMENT=53 DEFAULT CHARSET=utf8;
56
57 -- ----------------------------
58 -- Records of `score`
59 -- ----------------------------
60 BEGIN;
61 INSERT INTO `score` VALUES ('1', '1', '1', '10'), ('2', '1', '2', '9'), ('5', '1', '4', '66'), ('6', '2', '1', '8'), ('8', '2', '3', '68'), ('9', '2', '4', '99'), ('10', '3', '1', '77'), ('11', '3', '2', '66'), ('12', '3', '3', '87'), ('13', '3', '4', '99'), ('14', '4', '1', '79'), ('15', '4', '2', '11'), ('16', '4', '3', '67'), ('17', '4', '4', '100'), ('18', '5', '1', '79'), ('19', '5', '2', '11'), ('20', '5', '3', '67'), ('21', '5', '4', '100'), ('22', '6', '1', '9'), ('23', '6', '2', '100'), ('24', '6', '3', '67'), ('25', '6', '4', '100'), ('26', '7', '1', '9'), ('27', '7', '2', '100'), ('28', '7', '3', '67'), ('29', '7', '4', '88'), ('30', '8', '1', '9'), ('31', '8', '2', '100'), ('32', '8', '3', '67'), ('33', '8', '4', '88'), ('34', '9', '1', '91'), ('35', '9', '2', '88'), ('36', '9', '3', '67'), ('37', '9', '4', '22'), ('38', '10', '1', '90'), ('39', '10', '2', '77'), ('40', '10', '3', '43'), ('41', '10', '4', '87'), ('42', '11', '1', '90'), ('43', '11', '2', '77'), ('44', '11', '3', '43'), ('45', '11', '4', '87'), ('46', '12', '1', '90'), ('47', '12', '2', '77'), ('48', '12', '3', '43'), ('49', '12', '4', '87'), ('52', '13', '3', '87');
62 COMMIT;
63
64 -- ----------------------------
65 -- Table structure for `student`
66 -- ----------------------------
67 DROP TABLE IF EXISTS `student`;
68 CREATE TABLE `student` (
69 `sid` int(11) NOT NULL AUTO_INCREMENT,
70 `gender` char(1) NOT NULL,
71 `class_id` int(11) NOT NULL,
72 `sname` varchar(32) NOT NULL,
73 PRIMARY KEY (`sid`),
74 KEY `fk_class` (`class_id`),
75 CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`)
76 ) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8;
77
78 -- ----------------------------
79 -- Records of `student`
80 -- ----------------------------
81 BEGIN;
82 INSERT INTO `student` VALUES ('1', '男', '1', '理解'), ('2', '女', '1', '钢蛋'), ('3', '男', '1', '张三'), ('4', '男', '1', '张一'), ('5', '女', '1', '张二'), ('6', '男', '1', '张四'), ('7', '女', '2', '铁锤'), ('8', '男', '2', '李三'), ('9', '男', '2', '李一'), ('10', '女', '2', '李二'), ('11', '男', '2', '李四'), ('12', '女', '3', '如花'), ('13', '男', '3', '刘三'), ('14', '男', '3', '刘一'), ('15', '女', '3', '刘二'), ('16', '男', '3', '刘四');
83 COMMIT;
84
85 -- ----------------------------
86 -- Table structure for `teacher`
87 -- ----------------------------
88 DROP TABLE IF EXISTS `teacher`;
89 CREATE TABLE `teacher` (
90 `tid` int(11) NOT NULL AUTO_INCREMENT,
91 `tname` varchar(32) NOT NULL,
92 PRIMARY KEY (`tid`)
93 ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;
94
95 -- ----------------------------
96 -- Records of `teacher`
97 -- ----------------------------
98 BEGIN;
99 INSERT INTO `teacher` VALUES ('1', '张磊老师'), ('2', '李平老师'), ('3', '刘海燕老师'), ('4', '朱云海老师'), ('5', '李杰老师');
100 COMMIT;
101
102 SET FOREIGN_KEY_CHECKS = 1;
1 2、查询“生物”课程比“物理”课程成绩高的所有学生的学号；
2 思路：
3 获取所有有生物课程的人（学号，成绩） - 临时表
4 获取所有有物理课程的人（学号，成绩） - 临时表
5 根据【学号】连接两个临时表：
6 学号 物理成绩 生物成绩
7
8 然后再进行筛选
9
10 select A.student_id,sw,ty from
11
12 (select student_id,num as sw from score left join course on score.course_id = course.cid where course.cname = '生物') as A
13
14 left join
15
16 (select student_id,num as ty from score left join course on score.course_id = course.cid where course.cname = '体育') as B
17
18 on A.student_id = B.student_id where sw > if(isnull(ty),0,ty);
19
20 3、查询平均成绩大于60分的同学的学号和平均成绩；
21 思路：
22 根据学生分组，使用avg获取平均值，通过having对avg进行筛选
23
24 select student_id,avg(num) from score group by student_id having avg(num) > 60
25
26 4、查询所有同学的学号、姓名、选课数、总成绩；
27
28 select score.student_id,sum(score.num),count(score.student_id),student.sname
29 from
30 score left join student on score.student_id = student.sid
31 group by score.student_id
32
33 5、查询姓“李”的老师的个数；
34 select count(tid) from teacher where tname like '李%'
35
36 select count(1) from (select tid from teacher where tname like '李%') as B
37
38 6、查询没学过“叶平”老师课的同学的学号、姓名；
39 思路：
40 先查到“李平老师”老师教的所有课ID
41 获取选过课的所有学生ID
42 学生表中筛选
43 select * from student where sid not in (
44 select DISTINCT student_id from score where score.course_id in (
45 select cid from course left join teacher on course.teacher_id = teacher.tid where tname = '李平老师'
46 )
47 )
48
49 7、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名；
50 思路：
51 先查到既选择001又选择002课程的所有同学
52 根据学生进行分组，如果学生数量等于2表示，两门均已选择
53
54 select student_id,sname from
55
56 (select student_id,course_id from score where course_id = 1 or course_id = 2) as B
57
58 left join student on B.student_id = student.sid group by student_id HAVING count(student_id) > 1
59
60
61 8、查询学过“叶平”老师所教的所有课的同学的学号、姓名；
62
63 同上，只不过将001和002变成 in (叶平老师的所有课)
64
65 9、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；
66 同第1题
67
68
69 10、查询有课程成绩小于60分的同学的学号、姓名；
70
71 select sid,sname from student where sid in (
72 select distinct student_id from score where num < 60
73 )
74
75 11、查询没有学全所有课的同学的学号、姓名；
76 思路：
77 在分数表中根据学生进行分组，获取每一个学生选课数量
78 如果数量 == 总课程数量，表示已经选择了所有课程
79
80 select student_id,sname
81 from score left join student on score.student_id = student.sid
82 group by student_id HAVING count(course_id) = (select count(1) from course)
83
84
85 12、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；
86 思路：
87 获取 001 同学选择的所有课程
88 获取课程在其中的所有人以及所有课程
89 根据学生筛选，获取所有学生信息
90 再与学生表连接，获取姓名
91
92 select student_id,sname, count(course_id)
93 from score left join student on score.student_id = student.sid
94 where student_id != 1 and course_id in (select course_id from score where student_id = 1) group by student_id
95
96 13、查询至少学过学号为“001”同学所有课的其他同学学号和姓名；
97 先找到和001的学过的所有人
98 然后个数 ＝ 001所有学科 ＝＝》 其他人可能选择的更多
99
100 select student_id,sname, count(course_id)
101 from score left join student on score.student_id = student.sid
102 where student_id != 1 and course_id in (select course_id from score where student_id = 1) group by student_id having count(course_id) ＝ (select count(course_id) from score where student_id = 1)
103
104 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；
105
106 个数相同
107 002学过的也学过
108
109 select student_id,sname from score left join student on score.student_id = student.sid where student_id in (
110 select student_id from score where student_id != 1 group by student_id HAVING count(course_id) = (select count(1) from score where student_id = 1)
111 ) and course_id in (select course_id from score where student_id = 1) group by student_id HAVING count(course_id) = (select count(1) from score where student_id = 1)
112
113
114 15、删除学习“叶平”老师课的score表记录；
115
116 delete from score where course_id in (
117 select cid from course left join teacher on course.teacher_id = teacher.tid where teacher.name = '叶平'
118 )
119
120 16、向SC表中插入一些记录，这些记录要求符合以下条件：①没有上过编号“002”课程的同学学号；②插入“002”号课程的平均成绩；
121 思路：
122 由于insert 支持
123 inset into tb1(xx,xx) select x1,x2 from tb2;
124 所有，获取所有没上过002课的所有人，获取002的平均成绩
125
126 insert into score(student_id, course_id, num) select sid,2,(select avg(num) from score where course_id = 2)
127 from student where sid not in (
128 select student_id from score where course_id = 2
129 )
130
131 17、按平均成绩从低到高 显示所有学生的“语文”、“数学”、“英语”三门的课程成绩，按如下形式显示： 学生ID,语文,数学,英语,有效课程数,有效平均分；
132 select sc.student_id,
133 (select num from score left join course on score.course_id = course.cid where course.cname = "生物" and score.student_id=sc.student_id) as sy,
134 (select num from score left join course on score.course_id = course.cid where course.cname = "物理" and score.student_id=sc.student_id) as wl,
135 (select num from score left join course on score.course_id = course.cid where course.cname = "体育" and score.student_id=sc.student_id) as ty,
136 count(sc.course_id),
137 avg(sc.num)
138 from score as sc
139 group by student_id desc
140
141 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；
142
143 select course_id, max(num) as max_num, min(num) as min_num from score group by course_id;
144
145 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；
146 思路：case when .. then
147 select course_id, avg(num) as avgnum,sum(case when score.num > 60 then 1 else 0 END)/count(1)*100 as percent from score group by course_id order by avgnum asc,percent desc;
148
149 20、课程平均分从高到低显示（现实任课老师）；
150
151 select avg(if(isnull(score.num),0,score.num)),teacher.tname from course
152 left join score on course.cid = score.course_id
153 left join teacher on course.teacher_id = teacher.tid
154
155 group by score.course_id
156
157
158 21、查询各科成绩前三名的记录:(不考虑成绩并列情况)
159 select score.sid,score.course_id,score.num,T.first_num,T.second_num from score left join
160 (
161 select
162 sid,
163 (select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 0,1) as first_num,
164 (select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 3,1) as second_num
165 from
166 score as s1
167 ) as T
168 on score.sid =T.sid
169 where score.num <= T.first_num and score.num >= T.second_num
170
171 22、查询每门课程被选修的学生数；
172
173 select course_id, count(1) from score group by course_id;
174
175 23、查询出只选修了一门课程的全部学生的学号和姓名；
176 select student.sid, student.sname, count(1) from score
177
178 left join student on score.student_id = student.sid
179
180 group by course_id having count(1) = 1
181
182
183 24、查询男生、女生的人数；
184 select * from
185 (select count(1) as man from student where gender='男') as A ,
186 (select count(1) as feman from student where gender='女') as B
187
188 25、查询姓“张”的学生名单；
189 select sname from student where sname like '张%';
190
191 26、查询同名同姓学生名单，并统计同名人数；
192
193 select sname,count(1) as count from student group by sname;
194
195 27、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；
196 select course_id,avg(if(isnull(num), 0 ,num)) as avg from score group by course_id order by avg asc,course_id desc;
197
198 28、查询平均成绩大于85的所有学生的学号、姓名和平均成绩；
199
200 select student_id,sname, avg(if(isnull(num), 0 ,num)) from score left join student on score.student_id = student.sid group by student_id;
201
202 29、查询课程名称为“数学”，且分数低于60的学生姓名和分数；
203
204 select student.sname,score.num from score
205 left join course on score.course_id = course.cid
206 left join student on score.student_id = student.sid
207 where score.num < 60 and course.cname = '生物'
208
209 30、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；
210 select * from score where score.student_id = 3 and score.num > 80
211
212 31、求选了课程的学生人数
213
214 select count(distinct student_id) from score
215
216 select count(c) from (
217 select count(student_id) as c from score group by student_id) as A
218
219 32、查询选修“杨艳”老师所授课程的学生中，成绩最高的学生姓名及其成绩；
220
221 select sname,num from score
222 left join student on score.student_id = student.sid
223 where score.course_id in (select course.cid from course left join teacher on course.teacher_id = teacher.tid where tname='张磊老师') order by num desc limit 1;
224
225 33、查询各个课程及相应的选修人数；
226 select course.cname,count(1) from score
227 left join course on score.course_id = course.cid
228 group by course_id;
229
230
231 34、查询不同课程但成绩相同的学生的学号、课程号、学生成绩；
232 select DISTINCT s1.course_id,s2.course_id,s1.num,s2.num from score as s1, score as s2 where s1.num = s2.num and s1.course_id != s2.course_id;
233
234 35、查询每门课程成绩最好的前两名；
235
236 select score.sid,score.course_id,score.num,T.first_num,T.second_num from score left join
237 (
238 select
239 sid,
240 (select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 0,1) as first_num,
241 (select num from score as s2 where s2.course_id = s1.course_id order by num desc limit 1,1) as second_num
242 from
243 score as s1
244 ) as T
245 on score.sid =T.sid
246 where score.num <= T.first_num and score.num >= T.second_num
247
248 36、检索至少选修两门课程的学生学号；
249 select student_id from score group by student_id having count(student_id) > 1
250
251 37、查询全部学生都选修的课程的课程号和课程名；
252 select course_id,count(1) from score group by course_id having count(1) = (select count(1) from student);
253
254 38、查询没学过“叶平”老师讲授的任一门课程的学生姓名；
255 select student_id,student.sname from score
256 left join student on score.student_id = student.sid
257 where score.course_id not in (
258 select cid from course left join teacher on course.teacher_id = teacher.tid where tname = '张磊老师'
259 )
260 group by student_id
261
262 39、查询两门以上不及格课程的同学的学号及其平均成绩；
263
264 select student_id,count(1) from score where num < 60 group by student_id having count(1) > 2
265
266 40、检索“004”课程分数小于60，按分数降序排列的同学学号；
267 select student_id from score where num< 60 and course_id = 4 order by num desc;
268
269 41、删除“002”同学的“001”课程的成绩；
270 delete from score where course_id = 1 and student_id = 2
