创建下列表并创建相关约束
问题
1：查询出成绩表，而且student_id 后面要有对应的学生名，course_id 后面要有对应的课程名.
1 SELECT 2 score.sid, 3 score.student_id, 4 student.sname, 5 score.course_id, 6 course.cname, 7 score.number 8 FROM score 9 LEFT JOIN student 10 ON student.sid = score.student_id 11 LEFT JOIN course 12 ON course.cid = score.course_id
2：查询平均成绩大于60分的同学的学号和平均成绩
1 SELECT student_id,SUM(number)/COUNT(student_id) AS avg_number FROM score GROUP BY student_id HAVING avg_number>60;
3：查询所有同学的学号、姓名、选课数、总成绩
1 SELECT student.sid,student.sname,COUNT(score.student_id),SUM(number) FROM student,score WHERE student.sid=score.student_id GROUP BY score.student_id
4：查询姓“李”的老师的个数
1 SELECT COUNT(*) FROM teacher WHERE tname LIKE "李%";
5：查询学过“李平”老师课的同学的学号、姓名
1 SELECT student.sid,student.sname FROM student,score WHERE student.sid=score.student_id AND score.course_id = (SELECT tid FROM teacher WHERE tname='李平老师');
6：查询学过“1”并且也学过编号“2”课程的同学的学号、姓名
1 SELECT student.sid,student.sname FROM student,score WHERE student.sid=score.student_id AND score.course_id IN (1,2) GROUP BY student.sname HAVING COUNT(*)=2;
7：查询没学过“叶平”老师课的同学的学号、姓名
1 SELECT 2 sid, 3 sname 4 FROM student 5 WHERE sid NOT IN(SELECT 6 student.sid 7 FROM score, 8 student 9 WHERE student.sid = score.student_id 10 AND score.course_id IN(SELECT 11 tid 12 FROM teacher 13 WHERE tname = '李平老师'));
8：查询有课程成绩小于60分的同学的学号、姓名
1 SELECT student.sid,student.sname FROM student,score WHERE student.sid=score.student_id AND number<60 GROUP BY student.sname;
9：查询没有学全所有课的同学的学号、姓名
1 SELECT student.sid,student.sname FROM student,score WHERE student.sid=score.student_id GROUP BY student.sid HAVING COUNT(*)<(SELECT COUNT(*) FROM course);
创建表和数据
1 /*
2 Navicat Premium Data Transfer
3
4 Source Server : localhost
5 Source Server Type : MySQL
6 Source Server Version : 50624
7 Source Host : localhost
8 Source Database : sqlexam
9
10 Target Server Type : MySQL
11 Target Server Version : 50624
12 File Encoding : utf-8
13
14 Date: 10/21/2016 06:46:46 AM
15 */
16
17 SET NAMES utf8;
18 SET FOREIGN_KEY_CHECKS = 0;
19
20 -- ----------------------------
21 -- Table structure for `class`
22 -- ----------------------------
23 DROP TABLE IF EXISTS `class`;
24 CREATE TABLE `class` (
25 `cid` int(11) NOT NULL AUTO_INCREMENT,
26 `caption` varchar(32) NOT NULL,
27 PRIMARY KEY (`cid`)
28 ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
29
30 -- ----------------------------
31 -- Records of `class`
32 -- ----------------------------
33 BEGIN;
34 INSERT INTO `class` VALUES ('1', '三年二班'), ('2', '三年三班'), ('3', '一年二班'), ('4', '二年九班');
35 COMMIT;
36
37 -- ----------------------------
38 -- Table structure for `course`
39 -- ----------------------------
40 DROP TABLE IF EXISTS `course`;
41 CREATE TABLE `course` (
42 `cid` int(11) NOT NULL AUTO_INCREMENT,
43 `cname` varchar(32) NOT NULL,
44 `teacher_id` int(11) NOT NULL,
45 PRIMARY KEY (`cid`),
46 KEY `fk_course_teacher` (`teacher_id`),
47 CONSTRAINT `fk_course_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teacher` (`tid`)
48 ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
49
50 -- ----------------------------
51 -- Records of `course`
52 -- ----------------------------
53 BEGIN;
54 INSERT INTO `course` VALUES ('1', '生物', '1'), ('2', '物理', '2'), ('3', '体育', '3'), ('4', '美术', '2');
55 COMMIT;
56
57 -- ----------------------------
58 -- Table structure for `score`
59 -- ----------------------------
60 DROP TABLE IF EXISTS `score`;
61 CREATE TABLE `score` (
62 `sid` int(11) NOT NULL AUTO_INCREMENT,
63 `student_id` int(11) NOT NULL,
64 `course_id` int(11) NOT NULL,
65 `num` int(11) NOT NULL,
66 PRIMARY KEY (`sid`),
67 KEY `fk_score_student` (`student_id`),
68 KEY `fk_score_course` (`course_id`),
69 CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`),
70 CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`)
71 ) ENGINE=InnoDB AUTO_INCREMENT=53 DEFAULT CHARSET=utf8;
72
73 -- ----------------------------
74 -- Records of `score`
75 -- ----------------------------
76 BEGIN;
77 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');
78 COMMIT;
79
80 -- ----------------------------
81 -- Table structure for `student`
82 -- ----------------------------
83 DROP TABLE IF EXISTS `student`;
84 CREATE TABLE `student` (
85 `sid` int(11) NOT NULL AUTO_INCREMENT,
86 `gender` char(1) NOT NULL,
87 `class_id` int(11) NOT NULL,
88 `sname` varchar(32) NOT NULL,
89 PRIMARY KEY (`sid`),
90 KEY `fk_class` (`class_id`),
91 CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`)
92 ) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8;
93
94 -- ----------------------------
95 -- Records of `student`
96 -- ----------------------------
97 BEGIN;
98 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');
99 COMMIT;
100
101 -- ----------------------------
102 -- Table structure for `teacher`
103 -- ----------------------------
104 DROP TABLE IF EXISTS `teacher`;
105 CREATE TABLE `teacher` (
106 `tid` int(11) NOT NULL AUTO_INCREMENT,
107 `tname` varchar(32) NOT NULL,
108 PRIMARY KEY (`tid`)
109 ) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8;
110
111 -- ----------------------------
112 -- Records of `teacher`
113 -- ----------------------------
114 BEGIN;
115 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');
116 COMMIT;
117
118 SET FOREIGN_KEY_CHECKS = 1;
来源：https://www.cnblogs.com/sun-10387834/p/12367732.html