mysql基础练习题
一、表关系
请创建如下表，并创建相关约束
二、操作表
1、自行创建测试数据
/* Navicat MySQL Data Transfer Source Server : mysql5.7.1 Source Server Version : 50717 Source Host : localhost:3306 Source Database : crm Target Server Type : MYSQL Target Server Version : 50717 File Encoding : 65001 Date: 2017-02-24 09:50:15 */ SET FOREIGN_KEY_CHECKS=0; -- ---------------------------- -- Table structure for class -- ---------------------------- DROP TABLE IF EXISTS `class`; CREATE TABLE `class` ( `cid` int(11) NOT NULL AUTO_INCREMENT, `caption` varchar(32) NOT NULL, PRIMARY KEY (`cid`) ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of class -- ---------------------------- INSERT INTO `class` VALUES ('1', '三年二班'); INSERT INTO `class` VALUES ('2', '三年三班'); INSERT INTO `class` VALUES ('3', '一年二班'); INSERT INTO `class` VALUES ('4', '二年九班'); -- ---------------------------- -- Table structure for course -- ---------------------------- DROP TABLE IF EXISTS `course`; CREATE TABLE `course` ( `cid` int(11) NOT NULL AUTO_INCREMENT, `cname` varchar(32) NOT NULL, `teacher_id` int(11) NOT NULL, PRIMARY KEY (`cid`), KEY `fk_course_teacher` (`teacher_id`), CONSTRAINT `fk_course_teacher` FOREIGN KEY (`teacher_id`) REFERENCES `teacher` (`tid`) ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of course -- ---------------------------- INSERT INTO `course` VALUES ('1', '生物', '1'); INSERT INTO `course` VALUES ('2', '物理', '2'); INSERT INTO `course` VALUES ('3', '体育', '3'); INSERT INTO `course` VALUES ('4', '美术', '2'); -- ---------------------------- -- Table structure for score -- ---------------------------- DROP TABLE IF EXISTS `score`; CREATE TABLE `score` ( `sid` int(11) NOT NULL AUTO_INCREMENT, `student_id` int(11) NOT NULL, `course_id` int(11) NOT NULL, `num` int(11) NOT NULL, PRIMARY KEY (`sid`), KEY `fk_score_student` (`student_id`), KEY `fk_score_course` (`course_id`), CONSTRAINT `fk_score_course` FOREIGN KEY (`course_id`) REFERENCES `course` (`cid`), CONSTRAINT `fk_score_student` FOREIGN KEY (`student_id`) REFERENCES `student` (`sid`) ) ENGINE=InnoDB AUTO_INCREMENT=53 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of score -- ---------------------------- INSERT INTO `score` VALUES ('1', '1', '1', '10'); INSERT INTO `score` VALUES ('2', '1', '2', '9'); INSERT INTO `score` VALUES ('5', '1', '4', '66'); INSERT INTO `score` VALUES ('6', '2', '1', '8'); INSERT INTO `score` VALUES ('8', '2', '3', '68'); INSERT INTO `score` VALUES ('9', '2', '4', '99'); INSERT INTO `score` VALUES ('10', '3', '1', '77'); INSERT INTO `score` VALUES ('11', '3', '2', '66'); INSERT INTO `score` VALUES ('12', '3', '3', '87'); INSERT INTO `score` VALUES ('13', '3', '4', '99'); INSERT INTO `score` VALUES ('14', '4', '1', '79'); INSERT INTO `score` VALUES ('15', '4', '2', '11'); INSERT INTO `score` VALUES ('16', '4', '3', '67'); INSERT INTO `score` VALUES ('17', '4', '4', '100'); INSERT INTO `score` VALUES ('18', '5', '1', '79'); INSERT INTO `score` VALUES ('19', '5', '2', '11'); INSERT INTO `score` VALUES ('20', '5', '3', '67'); INSERT INTO `score` VALUES ('21', '5', '4', '100'); INSERT INTO `score` VALUES ('22', '6', '1', '9'); INSERT INTO `score` VALUES ('23', '6', '2', '100'); INSERT INTO `score` VALUES ('24', '6', '3', '67'); INSERT INTO `score` VALUES ('25', '6', '4', '100'); INSERT INTO `score` VALUES ('26', '7', '1', '9'); INSERT INTO `score` VALUES ('27', '7', '2', '100'); INSERT INTO `score` VALUES ('28', '7', '3', '67'); INSERT INTO `score` VALUES ('29', '7', '4', '88'); INSERT INTO `score` VALUES ('30', '8', '1', '9'); INSERT INTO `score` VALUES ('31', '8', '2', '100'); INSERT INTO `score` VALUES ('32', '8', '3', '67'); INSERT INTO `score` VALUES ('33', '8', '4', '88'); INSERT INTO `score` VALUES ('34', '9', '1', '91'); INSERT INTO `score` VALUES ('35', '9', '2', '88'); INSERT INTO `score` VALUES ('36', '9', '3', '67'); INSERT INTO `score` VALUES ('37', '9', '4', '22'); INSERT INTO `score` VALUES ('38', '10', '1', '90'); INSERT INTO `score` VALUES ('39', '10', '2', '77'); INSERT INTO `score` VALUES ('40', '10', '3', '43'); INSERT INTO `score` VALUES ('41', '10', '4', '87'); INSERT INTO `score` VALUES ('42', '11', '1', '90'); INSERT INTO `score` VALUES ('43', '11', '2', '77'); INSERT INTO `score` VALUES ('44', '11', '3', '43'); INSERT INTO `score` VALUES ('45', '11', '4', '87'); INSERT INTO `score` VALUES ('46', '12', '1', '90'); INSERT INTO `score` VALUES ('47', '12', '2', '77'); INSERT INTO `score` VALUES ('48', '12', '3', '43'); INSERT INTO `score` VALUES ('49', '12', '4', '87'); INSERT INTO `score` VALUES ('52', '13', '3', '87'); -- ---------------------------- -- Table structure for student -- ---------------------------- DROP TABLE IF EXISTS `student`; CREATE TABLE `student` ( `sid` int(11) NOT NULL AUTO_INCREMENT, `gender` char(1) NOT NULL, `class_id` int(11) NOT NULL, `sname` varchar(32) NOT NULL, PRIMARY KEY (`sid`), KEY `fk_class` (`class_id`), CONSTRAINT `fk_class` FOREIGN KEY (`class_id`) REFERENCES `class` (`cid`) ) ENGINE=InnoDB AUTO_INCREMENT=17 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of student -- ---------------------------- INSERT INTO `student` VALUES ('1', '男', '1', '刘洋'); INSERT INTO `student` VALUES ('2', '女', '1', '钢蛋'); INSERT INTO `student` VALUES ('3', '男', '1', '刘泽栋'); INSERT INTO `student` VALUES ('4', '男', '1', '张少博'); INSERT INTO `student` VALUES ('5', '女', '1', '张少强'); INSERT INTO `student` VALUES ('6', '男', '1', '王飞'); INSERT INTO `student` VALUES ('7', '女', '2', '铁锤'); INSERT INTO `student` VALUES ('8', '男', '2', '李三'); INSERT INTO `student` VALUES ('9', '男', '2', '李一'); INSERT INTO `student` VALUES ('10', '女', '2', '李二'); INSERT INTO `student` VALUES ('11', '男', '2', '李四'); INSERT INTO `student` VALUES ('12', '女', '3', '王鹏'); INSERT INTO `student` VALUES ('13', '男', '3', '刘明'); INSERT INTO `student` VALUES ('14', '男', '3', '刘刚'); INSERT INTO `student` VALUES ('15', '女', '3', '刘二'); INSERT INTO `student` VALUES ('16', '男', '3', '刘四'); -- ---------------------------- -- Table structure for teacher -- ---------------------------- DROP TABLE IF EXISTS `teacher`; CREATE TABLE `teacher` ( `tid` int(11) NOT NULL AUTO_INCREMENT, `tname` varchar(32) NOT NULL, PRIMARY KEY (`tid`) ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8; -- ---------------------------- -- Records of teacher -- ---------------------------- INSERT INTO `teacher` VALUES ('1', '马云老师'); INSERT INTO `teacher` VALUES ('2', '刘强东老师'); INSERT INTO `teacher` VALUES ('3', '马化腾老师'); INSERT INTO `teacher` VALUES ('4', '丁磊老师'); INSERT INTO `teacher` VALUES ('5', '王建宁老师'); INSERT INTO `teacher` VALUES ('6', '李杰老师');
2、操作
-- -- 1、自行创建测试数据 -- -- 2、查询“生物”课程比“物理”课程成绩高的所有学生的学号； -- SELECT -- A.student_id,A.num -- FROM -- ( -- SELECT -- score.sid, -- score.student_id, -- course.cname, -- score.num -- FROM -- score -- LEFT JOIN course ON score.course_id = course.cid -- WHERE -- course.cname = "生物" -- ) AS A -- -- INNER JOIN ( -- -- SELECT -- score.sid, -- score.student_id, -- course.cname, -- score.num -- FROM -- score -- LEFT JOIN course ON score.course_id = course.cid -- WHERE -- course.cname = "物理" -- ) AS B ON A.student_id = B.student_id -- WHERE -- A.num > B.num -- -- 3、查询平均成绩大于60分的同学的学号和平均成绩； -- SELECT -- B.student_id, -- student.sname, -- B.aa -- FROM -- ( -- SELECT -- student_id, -- avg(num) AS aa -- FROM -- score -- GROUP BY -- student_id -- HAVING -- avg(num) > 60 -- ) AS B -- LEFT JOIN student ON B.student_id = student.sid -- 4、查询所有同学的学号、姓名、选课数、总成绩； -- SELECT -- score.student_id, -- count(course_id), -- student.sname, -- sum(num) -- FROM -- score -- LEFT JOIN student ON score.student_id = student.sid -- GROUP BY -- score.student_id; -- -- -- 5、查询姓“李”的老师的个数； -- select tid from teacher where tname like '李%'; -- -- 6、查询没学过“李平”老师课的同学的学号、姓名； -- SELECT -- student.sid, -- student.sname -- FROM -- student -- WHERE -- sid NOT IN ( -- SELECT -- student_id -- FROM -- score -- WHERE -- course_id IN ( -- SELECT -- course.cid -- FROM -- course -- LEFT JOIN teacher ON course.teacher_id = teacher.tid -- WHERE -- teacher.tname = "李平老师" -- ) -- GROUP BY -- student_id -- ) -- -- -- 7、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_id, -- student.sname -- FROM -- ( -- SELECT -- student_id, -- course_id -- FROM -- score -- WHERE -- score.course_id = 1 -- OR score.course_id = 2 -- ) AS A -- LEFT JOIN student ON A.student_id = student.sid -- GROUP BY -- student_id -- HAVING -- count(student_id) > 1; -- -- 8、查询学过“李平”老师所教的所有课的同学的学号、姓名； -- SELECT -- student_id -- FROM -- score -- WHERE -- course_id IN ( -- SELECT -- cid -- FROM -- course -- LEFT JOIN teacher ON teacher_id = teacher.tid -- WHERE -- teacher.tname = "李平老师" -- ) -- GROUP BY -- student_id -- HAVING -- count(course_id) = ( -- SELECT -- count(cid) -- FROM -- course -- LEFT JOIN teacher ON teacher_id = teacher.tid -- WHERE -- teacher.tname = "李平老师" -- ) -- -- 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； -- SELECT -- -- A.student_id,A.num -- FROM -- ( -- SELECT -- score.sid, -- score.student_id, -- score.course_id, -- score.num -- FROM -- score -- LEFT JOIN course ON score.course_id = course.cid -- WHERE -- score.course_id = 1 -- ) AS A -- -- INNER JOIN -- -- ( -- SELECT -- score.sid, -- score.student_id, -- score.course_id, -- score.num -- FROM -- score -- LEFT JOIN course ON score.course_id = course.cid -- WHERE -- score.course_id = 2) -- -- AS B ON A.student_id = B.student_id -- WHERE -- A.num > B.num -- -- 10、查询有课程成绩小于60分的同学的学号、姓名； -- -- SELECT -- score.student_id, -- student.sname -- FROM -- score -- LEFT JOIN student ON score.student_id = student.sid -- WHERE -- score.num < 60 -- GROUP BY -- student_id; -- -- 11、查询没有学全所有课的同学的学号、姓名； -- select -- student_id, -- student.sname -- FROM -- score -- LEFT JOIN student ON score.student_id = student.sid -- GROUP BY -- score.student_id -- HAVING count(1) < (select count(cid) from course); -- -- -- 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； -- SELECT -- student_id, -- student.sname -- FROM -- score -- LEFT JOIN student ON score.student_id = student.sid -- WHERE -- student_id != 1 -- AND course_id IN ( -- SELECT -- course_id -- FROM -- score -- WHERE -- student_id = 1 -- ) -- GROUP BY -- student_id -- 13、查询至少学过学号为“001”同学所选课程中任意一门课的其他同学学号和姓名； -- select course_id from score where student_id=1; -- SELECT -- student_id, -- count(1) -- FROM -- score -- WHERE -- student_id != 1 -- AND course_id IN ( -- SELECT -- course_id -- FROM -- score -- WHERE -- student_id = 1 -- ) -- GROUP BY -- student_id -- HAVING -- count(1) = ( -- SELECT -- count(course_id) -- FROM -- score -- WHERE -- student_id = 1 -- ) -- -- 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； -- select count(1) from score where student_id=1; -- select student_id,sname from score LEFT JOIN student on score.student_id=student.sid where student_id in ( -- -- select student_id from score where student_id !=1 GROUP BY student_id HAVING count(1)=(select count(1) from score where student_id=1) -- -- )and course_id in(select course_id from score where student_id=1) GROUP BY student_id having count(1) =(select count(1) from score where student_id=1); -- -- -- 15、删除学习“李平”老师课的SC表记录； -- DELETE -- FROM -- score -- WHERE -- course_id IN ( -- SELECT -- cid -- FROM -- course -- LEFT JOIN teacher ON course.teacher_id = teacher.tid -- WHERE -- teacher.tname = "李平" -- ) -- -- -- 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； -- 插入表格 insert into tb(student_id,course_id,num) 映射里面加动态值 -- select student_id from score where course_id!=2 -- SELECT -- student_id, -- 2, -- ( -- SELECT -- AVG(num) -- FROM -- score -- WHERE -- course_id = 2 -- ) -- FROM -- score -- WHERE -- course_id != 2 -- 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； -- select student_id, -- (select num from score as s2 where s2.student_id=s1.student_id and course_id=1)as 语文, -- (select num from score as s2 where s2.student_id=s1.student_id and course_id=1)as 数学, -- (select num from score as s2 where s2.student_id=s1.student_id and course_id=1)as 英语 -- from score as s1; -- -- -- 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； -- SELECT -- course_id, -- MAX(num), -- min(num) -- FROM -- score -- GROUP BY -- course_id -- -- 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； -- 运用了 case when xx then xx else xx 判断语句 -- SELECT -- course_id, -- avg(num), -- sum( -- CASE -- WHEN num < 60 THEN -- 0 -- ELSE -- 1 -- END -- ), -- sum(1), -- sum( -- CASE -- WHEN num < 60 THEN -- 0 -- ELSE -- 1 -- END -- ) / sum(1) AS jgl -- FROM -- score -- GROUP BY -- course_id -- ORDER BY -- avg(num) ASC, -- jgl DESC; -- -- -- 20、课程平均分从高到低显示（现实任课老师）； -- 知识点 if(ISNULL(score.num),0,(score.num)) 三元运算 -- select score.course_id,avg(num),teacher.tname -- from score LEFT JOIN course on score.course_id=course.cid -- LEFT JOIN teacher on teacher.tid=course.teacher_id -- GROUP BY score.course_id ORDER BY avg(num)desc; -- -- -- 21、查询各科成绩前三名的记录:(不考虑成绩并列情况) -- select num from score where course_id =1 ORDER BY num desc LIMIT 0,1; -- select num from score where course_id =1 ORDER BY num desc LIMIT 1,1; -- select num from score where course_id =1 ORDER BY num desc LIMIT 2,1; -- select *from -- ( -- select student_id,course_id,num,1, -- (select num from score as s2 where s2.course_id=s1.course_id GROUP BY s2.num ORDER BY s2.num desc LIMIT 0,1), -- (select num from score as s2 where s2.course_id=s1.course_id GROUP BY s2.num ORDER BY s2.num desc LIMIT 3,1)as cc -- -- from score as s1 -- )as B -- where B.num >B.cc -- -- -- 22、查询每门课程被选修的学生数； -- select course_id,count(1) from score GROUP BY score.course_id -- 23、查询出只选修了一门课程的全部学生的学号和姓名； -- SELECT -- A.student_id, -- student.sname -- FROM -- ( -- SELECT -- student_id, -- count(1) -- FROM -- score -- GROUP BY -- student_id -- HAVING -- count(1) = 1 -- ) AS A -- LEFT JOIN student ON A.student_id = student.sid -- -- -- 24、查询男生、女生的人数； -- SELECT -- * -- FROM -- ( -- SELECT -- count(gender) AS F -- FROM -- student -- WHERE -- gender = "男" -- ) AS A, -- ( -- SELECT -- count(gender) AS M -- FROM -- student -- WHERE -- gender = "女" -- ) AS B -- -- -- 25、查询姓“张”的学生名单； -- select *from student where sname like "张%" -- -- 26、查询同名同姓学生名单，并统计同名人数； -- SELECT -- sname, -- count(sname) -- FROM -- student -- GROUP BY -- sname -- 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； -- select course_id,avg(if(isnull(num),0,num))as avg from score GROUP BY course_id ORDER BY avg asc,course_id desc; -- -- 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； -- 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 -- -- -- 29、查询课程名称为“生物”，且分数低于60的学生姓名和分数； -- select *from score where num<60 and course_id=(select cid from course where cname="生物") -- select student.sname,score.num from score LEFT JOIN course on score.course_id=course.cid -- LEFT JOIN student on score.student_id=student.sid where score.num <60 and course.cname="生物" -- -- -- 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； -- SELECT -- A.student_id, -- student.sname -- FROM -- ( -- SELECT -- * -- FROM -- score -- WHERE -- course_id = 3 -- AND score.num > 80 -- ) AS A -- LEFT JOIN student ON A.student_id = student.sid -- -- -- 31、求选了课程的学生人数 -- select student_id from score GROUP BY student_id -- -- 32、查询选修“张磊”老师所授课程的学生中，成绩最高的学生姓名及其成绩； -- SELECT -- sname, -- num -- FROM -- score -- LEFT JOIN student ON score.student_id = student.sid -- 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; -- -- -- 33、查询各个课程及相应的选修人数； -- select course.cname,count(1)from score LEFT JOIN course on score.course_id=course.cid GROUP BY course_id; -- -- -- 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； -- 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; -- -- -- -- -- 35、查询每门课程成绩最好的前两名； -- select *from -- ( -- select student_id,course_id,num,1, -- (select num from score as s2 where s2.course_id=s1.course_id GROUP BY s2.num ORDER BY s2.num desc LIMIT 0,1), -- (select num from score as s2 where s2.course_id=s1.course_id GROUP BY s2.num ORDER BY s2.num desc LIMIT 2,1)as cc -- -- from score as s1 -- )as B -- where B.num >B.cc -- -- 36、检索至少选修两门课程的学生学号； -- SELECT -- student_id, -- count(1) -- FROM -- score -- GROUP BY -- student_id -- HAVING -- count(1) > 1; -- 37、查询全部学生都选修的课程的课程号和课程名； -- SELECT -- course_id, -- count(1) -- FROM -- score -- GROUP BY -- course_id -- HAVING -- count(1) = (SELECT count(1) FROM student); -- 38、查询没学过“李平”老师讲授的任一门课程的学生姓名； -- SELECT -- * -- FROM -- student -- WHERE -- sid NOT IN ( -- SELECT -- student_id -- FROM -- score -- WHERE -- course_id IN ( -- SELECT -- cid -- FROM -- course -- LEFT JOIN teacher ON course.teacher_id = teacher.tid -- WHERE -- teacher.tname = "李平老师" -- ) -- ) -- 39、查询两门以上不及格课程的同学的学号及其平均成绩； -- 先对学生进行分组 对课程数进行统计，筛选分数小于60分 -- SELECT -- student_id, -- count(1) -- FROM -- score -- WHERE -- num < 60 -- GROUP BY -- student_id -- HAVING -- count(1) > 2; -- 40、检索“004”课程分数小于60，按分数降序排列的同学学号； -- 运用了排序方法，order by xx desc方法排序 -- -- SELECT -- student_id -- FROM -- score -- WHERE -- course_id = 4 -- AND num < 60 -- ORDER BY -- num DESC -- -- 41、删除“002”同学的“001”课程的成绩； -- 运用了表格的删除功能 delete from score表格； -- DELETE -- FROM -- score -- WHERE -- score.course_id = 1 -- AND score.student_id = 2
