数据库----那些sql语句,你都会了吗
/*
数据导入：
Navicat Premium Data Transfer
Source Server : localhost
Source Server Type : MySQL
Source Server Version : 50624
Source Host : localhost
Source Database : sqlexam
Target Server Type : MySQL
Target Server Version : 50624
File Encoding : utf-8
Date: 10/21/2016 06:46:46 AM
*/
SET NAMES utf8;
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`
------
BEGIN;
INSERT INTO `class` VALUES ('1', '三年二班'), ('2', '三年三班'), ('3', '一年二班'), ('4', '二年九班');
COMMIT;
------
-- 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`
------
BEGIN;
INSERT INTO `course` VALUES ('1', '生物', '1'), ('2', '物理', '2'), ('3', '体育', '3'), ('4', '美术', '2');
COMMIT;
------
-- 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`
------
BEGIN;
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');
COMMIT;
------
-- 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`
------
BEGIN;
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');
COMMIT;
------
-- 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=6 DEFAULT CHARSET=utf8;
------
-- Records of `teacher`
------
BEGIN;
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');
COMMIT;
SET FOREIGN_KEY_CHECKS = 1;
init.sql
从init.sql文件中导入数据
#准备表、记录
mysql> create database db1;
mysql> use db1;
mysql> source /Python笔记\数据库\picture.png
)
1、查询男生、女生的人数；
select gender, count(gender) from student group by gender;
2、查询姓“张”的学生名单；
select sname from student where sname like ('张%');
3、课程平均分从高到低显示
select student_id,avg(num) from score group by student_id;
4、查询有课程成绩小于60分的同学的学号、姓名；
select sid,sname from student where sid in ( select distinct student_id from score where num<60);
5、查询至少有一门课与学号为1的同学所学课程相同的同学的学号和姓名；
select m.student_id,sname from student right join(select distinct student_id from score where student_id !=1 and course_id in (select course_id from score where student_id=1)
) as m on m.student_id=student.sid;
6、查询出只选修了一门课程的全部学生的学号和姓名；
select sid,sname from student where sid in ( select student_id from score group by student_id having count(course_id)=1);
7、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
8、查询课程编号“2”的成绩比课程编号“1”课程低的所有同学的学号、姓名；
select sid,sname from student where sid in (select t1.student_id from (select * from score where course_id =2) t2 inner join (select * from score where course_id =1) t1 on t2.student_id=t1.student_id where t2.num<t1.num);
9、查询“生物”课程比“物理”课程成绩高的所有学生的学号；
select t1.student_id from (select student_id,num from score where course_id =(select cid from course where cname='生物')) t1 inner join (select student_id,num from score where course_id =(select cid from course where cname='物理')) t2 on t1.student_id=t2.student_id where t1.num>t2.num;
10、查询平均成绩大于60分的同学的学号和平均成绩;
select student_id,avg(num) from score group by student_id having avg(num)>60;
11、查询所有同学的学号、姓名、选课数、总成绩；
select t.student_id,s.sname,count(t.sid),sum(num) from (select * from score s inner join course c on c.cid=s.course_id) t inner join student s on s.sid=t.student_id group by t.student_id;
12、查询姓“李”的老师的个数；
select count(tid) from teacher where tname like '李%';
13、查询没学过“张磊老师”课的同学的学号、姓名；
select s.sid,s.sname from student s left join(select student_id from score where course_id=(select cid from course where teacher_id=(select tid from teacher where tname='张磊老师'))) t on t.student_id=s.sid where t.student_id is null;
14、查询学过“1”并且也学过编号“2”课程的同学的学号、姓名；
select sid,sname from student where sid in (select t1.student_id from (select * from score where course_id=1) t1 inner join (select * from score where course_id=2) t2 on t1.student_id=t2.student_id) ;
15、查询学过“李平老师”所教的所有课的同学的学号、姓名；
select sid,sname from student where sid in (select student_id from score inner join (select * from course where teacher_id=(select tid from teacher where tname='李平老师' )) c on c.cid=course_id group by student_id having count(sid)<2);
1、查询没有学全所有课的同学的学号、姓名；
select sid,sname from student where sid in (select student_id from score group by student_id having count(sid)=4);
2、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 sid,sname from student where sid in (select s.student_id from score s right join (select course_id from score where student_id=2) t on t.course_id=s.course_id group by s.student_id having count(s.student_id)=3);
3、删除学习“叶平”老师课的SC表记录；
delete from score where course_id in (select tid from teacher where tname='叶平老师');
4、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；
select sid from student where sid not in (select student_id from score where course_id=2);
select course_id,avg(num) avg_num from score where course_id =2;
insert into score(student_id,course_id,num) (select * from (select sid from student where sid not in (select student_id from score where course_id=2)) t1 ,(select course_id ,avg(num) from score where course_id =2) t2);
5、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 * from
(select student_id,num,count(student_id) Chinese_num from score s inner join course c on s.course_id = c.cid where c.cname = '语文' group by student_id having num != 0) t1 left join
(select student_id,num Math_num from score s inner join course c on s.course_id = c.cid where c.cname = '数学') t2 on t1.student_id =t2.student_id
left join
(select student_id,num English_num from score s inner join course c on s.course_id = c.cid where c.cname = '英语') t3 on t3.student_id=t2.student_id
6、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
7、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；
select m1.course_id, m1.avg_num,m2.p from(select course_id,avg(num) avg_num from score group by course_id) m1 inner join(select t1.course_id,t1.num1/t2.num2 p from
(select course_id,count(*) num1 from score where num>=60 group by course_id) t1 inner join (select course_id,count(*) num2 from score group by course_id) t2 on t1.course_id=t2.course_id) m2 on m1.course_id=m2.course_id order by m1.avg_num,m2.p desc;
8、查询各科成绩前三名的记录:(不考虑成绩并列情况)
select sid,course_id,
(select student_id from score as s2 where s2.course_id = s1.course_id order by course_id num desc limit 0, 1) as first_num from score as s1
select sid,course_id,num,
(select student_id from score as s2 where s2.course_id = s1.course_id order by num desc,sid limit 1, 1) as second_sid from score as s1 order by course_id,num desc;
select sid,course_id,num,
(select student_id from score as s2 where s2.course_id = s1.course_id order by num desc,sid limit 2, 1) as third_sid from score as s1 order by course_id,num desc;
不考虑并列的前三名
select
t1.sid,t1.student_id,t1.course_id,t1.num from score t1
left join
(
select sid,course_id,
(select student_id from score as s2 where s2.course_id = s1.course_id order by num desc,sid limit 0, 1) as first_sid ,
(select student_id from score as s2 where s2.course_id = s1.course_id order by num desc,sid limit 1, 1) as second_sid ,
(select student_id from score as s2 where s2.course_id = s1.course_id order by num desc,sid limit 2, 1) as third_sid
from score as s1
) t2
on t1.sid = t2.sid
where t1.student_id = t2.first_sid or t1.student_id = t2.second_sid or t1.student_id = t2.third_sid;
考虑并列的前三名
select
t1.sid,t1.student_id,t1.course_id,t1.num from score t1
left join
(
select sid,course_id,
(select distinct num from score as s2 where s2.course_id = s1.course_id order by num desc limit 0, 1) as first_num,
(select distinct num from score as s2 where s2.course_id = s1.course_id order by num desc limit 1, 1) as second_num,
(select distinct num from score as s2 where s2.course_id = s1.course_id order by num desc limit 2, 1) as third_num
from score as s1
) t2
on t1.sid = t2.sid
where t1.num = t2.first_num or t1.num = t2.second_num or t1.num = t2.third_num;
select
t1.id,t1.classid,t1.studentid,t1.courseid,t1.score from test1 t1
left join
(
select id,courseid,
(select studentid from test1 as s2 where s2.courseid = s1.courseid order by score desc,id limit 0, 1) as first_sid ,
(select studentid from test1 as s2 where s2.courseid = s1.courseid order by score desc,id limit 1, 1) as second_sid ,
(select studentid from test1 as s2 where s2.courseid = s1.courseid order by score desc,id limit 2, 1) as third_sid
from test1 as s1
) t2
on t1.id = t2.id
where t1.studentid = t2.first_sid or t1.studentid = t2.second_sid or t1.studentid = t2.third_sid;
select id,courseid,
(select studentid from test1 as s2 where s2.courseid = s1.courseid and s2.classid=1 order by score desc,id limit 0, 1) as first_sid from test1 as s1
select id,courseid,
(select studentid from test1 as s2 where s2.courseid = s1.courseid order by score desc,id limit 0, 1) as first_sid ,
(select studentid from test1 as s2 where s2.courseid = s1.courseid order by score desc,id limit 1, 1) as second_sid,
(select studentid from test1 as s2 where s2.courseid = s1.courseid order by score desc,id limit 2, 1) as third_sid
from test1 as s1 order by courseid
select
* from test1 t1
left join
(
select id,courseid,
(select studentid from test1 as s2 where s2.courseid = s1.courseid order by score desc,id limit 0, 1) as first_sid ,
(select studentid from test1 as s2 where s2.courseid = s1.courseid order by score desc,id limit 1, 1) as second_sid ,
(select studentid from test1 as s2 where s2.courseid = s1.courseid order by score desc,id limit 2, 1) as third_sid
from test1 as s1
) t2
on t1.id = t2.id order by t1.courseid
insert into test1(classid,courseid,studentid,score) values(1,1,1,70),(1,2,1,45),(1,1,2,80),(1,2,2,75),(1,1,3,70),(1,2,3,75),(1,1,4,90),(1,2,4,73),(2,1,5,70),(2,2,5,45),(2,1,6,80),(2,2,6,75),(2,1,7,70),(2,2,7,75),(2,1,8,90),(2,2,8,73);
9、查询每门课程被选修的学生数；
select cname,t.n from(select course_id, count(*) n from score group by course_id) t
inner join course c on t.course_id = c.cid
10、查询同名同姓学生名单，并统计同名人数；
select sname, count(*) from student group by sname having count(*)>1;
11、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 c.cname, course_id,avg(num) from score s inner join course c on s.course_id=c.cid
group by course_id order by avg(num) ,course_id desc;
12、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 c.sid, c.sname,avg(num) from score s inner join student c on s.student_id=c.sid
group by s.student_id having avg(num)>85;
13、查询课程名称为“数学”，且分数低于60的学生姓名和分数；
select c.cname,s.num from score s inner join course c on s.course_id=c.cid where c.cname='数学' and num<60;
14、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 c.sid,c.sname from score s inner join student c on s.student_id=c.sid where s.course_id=3 and num>80;
15、求选了课程的学生人数
select count(distinct student_id) from score ;
16、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；
select c.sname,num from score s inner join student c on student_id=c.sid
where course_id in(select cid from teacher inner join course on teacher_id=tid where tname='杨艳老师') order by num desc limit 1;
17、查询各个课程及相应的选修人数；
select c.cname, count(s.sid) from score s inner join course c on s.course_id=c.cid group by s.course_id;
18、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 s.student_id,s.course_id,s.num from score s,(select student_id,course_id,num from score) t where t.course_id != s.course_id and t.num=s.num and t.student_id=s.student_id;
19、查询每门课程成绩最好的前两名；
20、检索至少选修两门课程的学生学号；
select student_id from score group by student_id having count(course_id)>1;
21、查询全部学生都选修的课程的课程号和课程名；
select s.course_id,c.cname from score s inner join course c on s.course_id= c.cid group by s.course_id having count(sid)>=(select count(*) num from student );
22、查询没学过“叶平”老师讲授的任一门课程的学生姓名；
select sid,sname from student where sid not in (select distinct student_id from score s inner join course c on s.course_id= c.cid where teacher_id=(select tid from teacher where name = '李平老师'));
23、查询两门以上不及格课程的同学的学号及其平均成绩；
select d.sid,d.sname,avg(num) from score s left join student d on s.student_id=d.sid where s.student_id in (select sid from score where num<60 group by student_id having count(*)>2);
24、检索“004”课程分数小于60，按分数降序排列的同学学号；
select d.sid,d.sname from score s inner join student d on s.student_id=d.sid where s.course_id=4 and s.num<60 order by s.num;
25、删除“002”同学的“001”课程的成绩；
delete from score where course_id = 1 and studnet_id=2;
