dedecms 做的医院网站/seo综合查询平台官网

dedecms 做的医院网站,seo综合查询平台官网,网上做网站任务,公司网站有哪些重要性最近在学习MYSQL 数据库,在此mark 一下做过的sql 相关练习表结构如下:teacher表tidtnameclass表cidcaptioncourse表cidcnameteacher_idstudent表sidgenderclass_idsnamescore表sidstudent_idcourse_idnumclass :teacher : course : student :score : 根…

最近在学习MYSQL 数据库,在此mark 一下做过的sql 相关练习

表结构如下:

teacher表

tid

tname

class表

cid

caption

course表

cid

cname

teacher_id

student表

sid

gender

class_id

sname

score表

sid

student_id

course_id

num

class :

375e833c484bae6ea0db27669327cb78.png teacher : 

003576a4a08923747c310e9fcd4db7a5.png course :  

6c08e2a31671237f37cdd0adf9992356.png

student :

87d5570594f2ef2bd27842271adee5c7.pngscore : 

066c3491148debdb0b3c5d0bba91221d.png

根据以上图片建表并进行SQL 语句练习:  (本次练习使用的MySQL 版本为 8.0.21,系统为windows 10 系统)

1.自行创建测试数据库

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

/*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: 2020年10月8日09:02:02*/

SETNAMES utf8;SET FOREIGN_KEY_CHECKS = 0;--------------------------------Table structure for `class`------------------------------

DROP TABLE IF EXISTS`class`;CREATE TABLE`class` (

`cid`int(11) NOT NULLAUTO_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 NULLAUTO_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 NULLAUTO_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 NULLAUTO_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 NULLAUTO_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;

View Code

2.查询 生物 课程比 物理 课程成绩高的所有学生的学号

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

--我的写法:

select A.student_id from score asAleft join score as B on A.student_id =B.student_idwhere A.course_id in (select cid from course where cname = '生物')and B.course_id in (select cid from course where cname = '物理')and A.num >B.num;--参考写法:

select A.student_id from(select score.sid, student_id,course.cname,num from score left join course on course.cid = score.course_id where course.cname = '生物') asAinner join(select score.sid,student_id,course.cname,num from score left join course on course.cid = score.course_id where course.cname = '物理') asBon A.student_id =B.student_idwhere A.num > B.num;

View Code

3.查询平均成绩大于60分的同学的学号和平均成绩

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select b.student_id,student.sname,B.avgnum from(select student_id ,AVG( num) as avgnum fromscoreGROUP BY student_id having AVG(num) > 60

ORDER BY avg(num) desc) asBLEFT JOIN student on B.student_id = student.sid ;

View Code

4.查询所有同学的学号,姓名,选课数,总成绩

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select student.sid,student.sname,Count(score.course_id),sum(score.num) fromstudentleft join score on score.student_id =student.sidGROUP BY student.sid;

View Code

5.查询姓李的老师的个数

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select '姓李的老师个数',count(1) from teacher where tname like '李%';

View Code

6.查询没学过 叶平 老师课的同学的学号和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select sa.sid,sa.sname from student assaWHERE sa.sid not in(select score.student_id fromscoreleft join student on score.student_id =student.sidleft join course on course.cid =score.course_idleft join teacher on teacher.tid =course.teacher_idwhere teacher.tname like '李平%');

View Code

7.查询学过 001 并且也学过编号 002 课程的同学的学号和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select score.student_id,student.sname fromscoreleft join student on student.sid =score.student_idwhere score.course_id = 1 or score.course_id = 2

GROUP BY score.student_id having count(score.course_id) > 1 ;

View Code

8.查询学过 李平 老师所有课程的同学的学号和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select A.student_id,student.sname from score asAleft join student on student.sid =A.student_idwhere A.course_id in(SELECT course.cid fromcourseleft join teacher on teacher.tid =course.teacher_idwhere teacher.tname like '李平%')group by A.student_id having count(A.course_id) =(SELECT count(course.cid) fromcourseleft join teacher on teacher.tid =course.teacher_idwhere teacher.tname like '李平%');

View Code

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和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select A.student_id,student.sname from score asAinner join score as B on A.student_id =B.student_idleft join student on student.sid =A.student_idwhere A.course_id = 1 and B.course_id = 2 and A.num < B.num;

View Code

10 查询有课程成绩小于 60 分的同学的学号和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select student_id,sname fromscoreleft join student on student.sid =score.student_idwhere score.num < 60

group byscore.student_id;select sid,sname from student where sid in(select student_id from score where num < 60 GROUP BYstudent_id);select sid,sname from student where sid in(select distinct student_id from score where num < 60) ; --distinct 的效率不高,能不用就不用,用其他方法实现去重

View Code

11.查询没有学全所有课程的同学的学号和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

--解答分析:--1.查出所有课程ID--2.查出所有学过所有课程的学生ID--3.从所有学生中去掉 上面查询出来的学生

--主要:这道题有一个题目理解的问题,就是"没有学全所有课程的学生"包不包括一门课没选的学生?--如果理解为包括,则是答案1的解法--如果理解为不包括,则是答案2、3 的解法

--答案一:

select sid,sname fromstudentwhere sid not in(select student_id fromscoreGROUP BY student_id having count(1) = ( select count(1) fromcourse)

);--答案二:

select student.sid,student.sname fromstudentleft JOIN score on score.student_id =student.sidGROUP BY student.sid having count(score.course_id) >= 1 and count(score.course_id) < ( select count(1) fromcourse) ;--答案三:

select student_id ,sname fromscoreleft join student on student.sid =score.student_idGROUP BY student_id HAVING count(1)

View Code

12.查询至少有一门课与学号 001 的同学所学相同的同学的学号和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

--解答思路:--1.先查出001 的同学所学的课程ID--2.查score 表中student_id != 1 的学生的课程ID 在上面查出的范围内的数据

select student.sid,student.sname fromscoreleft join student on student.sid =score.student_idwhere student_id != 1 and score.course_id in (select B.course_id from score as B where B.student_id = 1)GROUP BY score.student_id;

View Code

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

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select student.sid,student.sname fromscoreleft join student on student.sid =score.student_idwhere student_id != 1 and course_id in (SELECT course_id from score where student_id = 1)GROUP BY score.student_id having count(score.course_id) >= (select count(1) from score where student_id = 1);

View Code

14.查询 和 002 号同学学习的课程完全相同的其他同学的学号和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select score.student_id,student.sname fromscoreleft join student on student.sid =score.student_idwhere student_id in(select student_id fromscorewhere student_id != 2

GROUP BY student_id having count(course_id ) = (select count(1) from score where student_id = 2))and course_id in (select course_id from score where student_id = 2)GROUP BY student_id having count(course_id) = (select count(1) from score where student_id = 2);

View Code

15.删除学习 '叶平' 老师课的score表记录

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

delete fromscorewhere course_id in(select course.cid fromcourseleft join teacher on teacher.tid =course.teacher_idwhere tname like '叶平%');

View Code

16.向score 表插入一些记录,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

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select sid,2,(select avg(num) from score where course_id = 2 ) fromstudentwhere sid not in (select student_id from score where course_id = 2);

View Code

17、按平均成绩从低到高显示所有学生的 生物,物理,体育 三门的课程成绩,按如下形式显示: 学生ID,生物,物理,体育,有效课程数,有效平均分;

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select A.sid as学生ID,

(SELECT num from score left JOIN course on course.cid = score.course_id where course.cname = '生物' and score.student_id = A.sid) as生物,

(SELECT num from score left JOIN course on course.cid = score.course_id where course.cname = '物理' and score.student_id = A.sid) as物理,

(SELECT num from score left JOIN course on course.cid = score.course_id where course.cname = '体育' and score.student_id = A.sid) as体育,

(SELECT count(1) from score where score.student_id =A.sidand num is not null and score.course_id in(select cid from course where cname in ('生物','物理','体育'))) as有效课程数,

(SELECT avg(num) from score where score.student_id =A.sidand num is not null and score.course_id in(select cid from course where cname in ('生物','物理','体育'))) as三门成绩有效平均分from student asAleft join score on score.student_id =A.sidGROUP BY A.sid;

View Code

18.查询各科成绩最高分和最低分,以如下形式显示:课程ID,最高分,最低分

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

selectcourse.cidas课程ID ,max(score.num) as最高分,min(score.num) as最低分 .fromcourseleft JOIN score on score.course_id =course.cidGROUP BY course.cid;

View Code

19.按各科平均成绩从低到高和及格率的百分比从高到低顺序

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

selectA.cidas课程ID,avg(num) as课程平均分,AVG(A.passed ) 及格率from (select course_id as cid,num,case when num >=60 then 1 else 0 end as passed from score ) asAGROUP BYA.cidORDER BY avg(num) asc ,AVG(A.passed ) desc;selectcourse_idas课程ID,avg(num) as课程平均分,AVG(case when num >=60 then 1 else 0 end ) as及格率fromscoreGROUP BYcourse_idORDER BY avg(num) asc ,AVG(case when num >=60 then 1 else 0 end ) desc;

View Code

20.课程平均分从高到低显示(显示任课老师)

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

selectcourse.cidas课程ID,avg(score.num) as平均分,

teacher.tnameas授课老师fromcourseleft join score on score.course_id =course.cidleft join teacher on teacher.tid =course.teacher_idGROUP BYcourse.cidorder by avg(score.num) desc;

View Code

21.查询个课程成绩前三名的记录(不考虑成绩并列情况)

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

selectA.course_id,

A.student_id,

A.numfrom score asAwhere num >= (select num from score where course_id = A.course_id ORDER BY num desc LIMIT 2,1)ORDER BY A.course_id asc ,A.num desc;SELECTscore.course_id,score.student_id,score.numfromscoreleft JOIN(selectA.course_id,

(select num from score where score.course_id = A.course_id ORDER BY num desc LIMIT 2,1) asnumfrom score asAGROUP BYcourse_id

)as B on score.course_id =B.course_idwhere score.num >=B.numORDER BY score.course_id asc ,score.num desc;

View Code

22.查询每门课程被选修的学生数

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

SELECTcourse.cid ,count(score.course_id)fromcourseleft JOIN score on score.course_id =course.cidGROUP BY course.cid;

View Code

23.查询出只选修了一门课程的全部学生的学号和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select student.sid,student.sname fromscoreleft JOIN student on student.sid =score.student_idgroup by score.student_id having count(course_id) = 1;

View Code

24.查询男生、女生人数

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

SELECT gender,count(1) from student group by gender;

View Code

25.查询姓 张 的学生名单

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select * from student where sname like '张%';

View Code

26.查询同名同姓学生名单,并统计同名人数

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select sname ,COUNT(1) from student GROUP BY sname ;

View Code

27.查询每门课程的平均分,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

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select course.cid,avg( case when isnull(score.num) then 0 else score.num end) fromcourseLEFT JOIN score on score.course_id =course.cidGROUP BYcourse.cidORDER BY avg( case when isnull(score.num) then 0 else score.num END) asc ,score.course_id;

View Code

28.查询平均成绩大于 85 的所有学生的学号和姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select student.sid,student.sname,avg(num) fromscoreleft JOIN student on student.sid =score.student_idGROUP BY student_id having avg(num) > 60

ORDER BY avg(num) desc;

View Code

29 查询课程为 物理,且分数低于60 的学生的姓名和分数

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

SELECT course_id,student.sname,num fromscoreLEFT JOIN student on student.sid =score.student_idwhere course_id = (select cid from course where cname = "物理") and num < 60;

View Code

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

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

SELECT course_id,student.sname,num fromscoreLEFT JOIN student on student.sid =score.student_idwhere course_id = 3 and num >80;

View Code

31.求选了课程的学生人数

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select count(1) from score GROUP BY student_id;

View Code

32.查询选修 李平 老师所教授的学生中,成绩最高的学生姓名和成绩

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select score.course_id,score.student_id,student.sname,score.num fromscoreleft join(select course_id ,max(num) as num from score where course_id in(select cid from course where teacher_id = (select tid FROM teacher where tname like '李平%'))group by course_id ) asAon score.course_id =A.course_idleft join student on student.sid =score.student_idwhere score.num = A.num;

View Code

33.查询各个课程及相应的选修人数

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select course.cid,course.cname,count(score.student_id) fromcourseleft JOIN score on score.course_id =course.cidGROUP BY course.cid;

View Code

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

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

--不要在意这道题的结果,因为这个查询需求根本就是个奇葩

select a1.student_id, a1.course_id,a2.student_id,a2.course_id ,a2.num from score as a1 ,score asa2where (a1.student_id = a2.student_id and a1.course_id < a2.course_id and a1.num = a2.num )or(a1.student_id!= a2.student_id and a1.course_id != a2.course_id and a1.num =a2.num)ORDER BY a1.course_id asc;

View Code

35.查询每门课程成绩最好的前两名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

selectA.course_id,

A.student_id,

A.numfrom score asAwhere num >= (select num from score where course_id = A.course_id ORDER BY num desc LIMIT 1,1)ORDER BY A.course_id asc ,A.num desc;SELECTscore.course_id,score.student_id,score.numfromscoreleft JOIN(selectA.course_id,

(select num from score where score.course_id = A.course_id ORDER BY num desc LIMIT 1,1) asnumfrom score asAGROUP BYcourse_id

)as B on score.course_id =B.course_idwhere score.num >=B.numORDER BY score.course_id asc ,score.num desc;

View Code

36.检索至少选修两门课程的学生学号

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select student_id fromscoreGROUP BY student_id having count(course_id) >=2;

View Code

37.查询全部学生都选修的课程的课程号和课程名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select score.course_id,course.cname fromscoreleft JOIN course on course.cid =score.course_idgroup by course_id having count(student_id) = (select count(1) from student);

View Code

38.查询没学过 叶平 老师讲授的任意一门课程的学生姓名

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select sname fromstudentwhere sid not in(select student_id fromscorewhere course_id in(select cid fromcourseleft JOIN teacher on teacher.tid =course.teacher_idwhere tname like '李平%')

);

View Code

39.查询两门以上不及格课程的学生的学号及平均成绩

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select student_id,avg(num) fromscorewhere num <60

GROUP BY student_id having count(1)>=2 ;

View Code

40.检索 004 课程分数小于60,按分数降序排列的同学学号

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

select student_id,num fromscorewhere course_id = 4 and num < 60

order by num desc;

View Code

41删除 002 同学的 001 课程成绩

8f900a89c6347c561fdf2122f13be562.png

961ddebeb323a10fe0623af514929fc1.png

delete fromscorewhere student_id = 2 and course_id = 1;

View Code

终于吐血整理完了,撒花  ✿✿ヽ(°▽°)ノ✿

这些题目参考自 武沛齐老师博客园: https://www.cnblogs.com/ wupeiqi

答案均是我解答出来的,如有错误,欢迎提出指正。转载请标明出处!

本文来自互联网用户投稿,该文观点仅代表作者本人,不代表本站立场。本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如若转载,请注明出处:http://www.mzph.cn/news/443089.shtml

如若内容造成侵权/违法违规/事实不符,请联系多彩编程网进行投诉反馈email:809451989@qq.com,一经查实,立即删除!

相关文章

java 判断子类_java判断class是否是某个类的子类或父类

Class c = ArrayList.class; c.isPrimitive(); //判断c是否为基本数据类型 c.isAssignableFrom(List.class); //判断c是否是List类的子类或父类 c.getGenericType(); //得到泛型类型 免费学习视频分享:java视频教程 实例:通过反射得到List 集合中的泛型类型package com.zf.ta…

Java游戏有易筋经_易筋经- JavaWeb-1

JavaScript一种直译式脚本语言&#xff0c;是一种动态类型、弱类型、基于原型的语言&#xff0c;内置支持类型。它的解释器被称为JavaScript引擎&#xff0c;为浏览器的一部分&#xff0c;广泛用于客户端的脚本语言组成部分:ECMAScript:js基础语法(规定 关键字 运算符 语句 函数…

java导出hbase表数据_通用MapReduce程序复制HBase表数据

编写MR程序&#xff0c;让其可以适合大部分的HBase表数据导入到HBase表数据。其中包括可以设置版本数、可以设置输入表的列导入设置(选取其中某几列)、可以设置输出表的列导出设置(选取其中某几列)。原始表test1数据如下&#xff1a;每个row key都有两个版本的数据&#xff0c;…

java服务器和linux_在Linux下开一个Java服务器(使用CatServer Pro)

引言Linux开服具有快速&#xff0c;高效&#xff0c;性能等特点&#xff0c;而Windows虽然简单&#xff0c;但是不具备Linux良好的性能。本教程就说明一下简单的Linux开服方式(需要教程的人&#xff0c;如果你学会后&#xff0c;请无偿帮助更多的人。)服务器准备首先。先准备一…

我的世界java版游戏崩溃_我的世界全攻略之-游戏崩溃的解决方法

我的世界崩溃怎么办&#xff1f;下面吾爱网小编给大家带来我的世界无法正常启动的解决方法,需要的朋友可以参考下。我的世界作为许多玩家都十分喜爱的模拟经营沙盘类游戏,经常有玩家反映在玩我的世界的时候,游戏总是会出现崩溃或者无法启动的情况,玩家在遇到的时候不知道怎么办…

vue3 新项目 - 搭建路由router

创建router/index 文件 main.ts 安装 router 然后 在 app下面 去 设置 路由出口

java如何获得相反的颜色_javascript – 如何根据当前颜色生成相反的颜色?

更新&#xff1a;GitHub上的生产就绪代码.我就是这样做的&#xff1a;>将HEX转换为RGB>反转R,G和B组件>将每个组件转换回HEX>用零和输出填充每个组件.function invertColor(hex) {if (hex.indexOf(#) 0) {hex hex.slice(1);}// convert 3-digit hex to 6-digits.…

wamp php启动不成功,wamp的mysql 启动失败解决

wamp启动失败&#xff0c;查看原因是mysql 启动失败首先查看mysql的启动日志命令&#xff1a;mysqld --console知道error报错的地方&#xff1a;然后百度了此报错&#xff0c;解决方法在my.ini中添加innodb_force_recovery 1发现这个会影响insert需要设置为 innodb_force_reco…

php复选框样式,如何自定义checkbox样式?附代码

本篇文章给大家带来的内容是关于如何自定义checkbox样式&#xff1f;附代码&#xff0c;有一定的参考价值&#xff0c;有需要的朋友可以参考一下&#xff0c;希望对你有所帮助。修改原生checkbox样式。效果原理1.利用CSS3属性 appearance。该属性(强制)更改(改变)默认(原生)样式…

JAVA用数据留给出师表排序,如果诸葛亮会编程,用Java写出师表...

继上一篇 "如果诸葛亮用C#写出师表..."后&#xff0c;站长想自己的第一语言是Java&#xff0c;虽然平时工作上用的不多&#xff0c;也用Java实现一遍吧&#xff0c;改改就是了&#xff0c;无非就是:C#的Console.WriteLine改为Java的System.out.println&#xff1b;C#…

linux下的安装命令行工具下载,linux系统程序安装(二)yum工具2-yum源及包下载

继续我们的yum工具应用之旅&#xff0c;yum工具之所以方便就是因为有方便的在线云库&#xff0c;实际工作中我们可能没办法链接互联网&#xff0c;或者我们想安装的程序原生源那么我们能不能用其他方式应用方便的yum源呢&#xff1f;一、使用光盘作为yum源1、将光盘挂载到/mnt目…

体积最小桌面linux,Tiny Core Linux - 体积最小的精简 Linux 操作系统发行版之一 (仅10多MB)...

Tiny Core Linux (TCL) 是一款极体积极小且高度可扩展的微型 Linux 发行版&#xff0c;它将一个 Linux 操作系统精简到仅有 10 多 MB 左右的大小&#xff0c;似乎小巧得有点让人叹为观止&#xff01;要知道无论是常见的 Ubuntu、CentOS、Debian 的体积动辄就是几百MB甚至要上GB…

linux新建samba账户,ubuntu上创建账户和samba用户

系统环境&#xff1a;Linux ubuntu152 3.2.0-23-generic #36-Ubuntu SMP Tue Apr 10 20:39:51 UTC 2012 x86_64 x86_64x86_64 GNU/Linux系统用户登录创建linux账户:1. sudo adduser username --home /home/username执行该命令后需要两次输入账户密码&#xff0c;连续回车&…

在c语言中优先级最低的是6,C语言中 *,<<,= ,->哪个优先级最低

满意答案nishiwodezmx推荐于 2016.03.13采纳率&#xff1a;46% 等级&#xff1a;12已帮助&#xff1a;6812人最高的是->(指向运算符)再到*再到>>(右移运算符)再到(赋值运算符)c语言运算符号:1级优先级 左结合() 圆括号[] 下标运算符-> 指向结构体成员运算符. 结…

队列的顺序数组c语言代码,队列-队列的顺序表示和实现

队列-队列的顺序表示和实现和顺序栈相类似&#xff0c;在利用顺序分配存储结构实现队列时&#xff0c;除了用一维数组描述队列中数据元素的存储区域之外&#xff0c;尚需设立两个指针front和rear分别指示“队头”和“队尾”的位置。为了在C语言中描述方便&#xff0c;在此我们约…

android 链接分享到朋友圈,android 分享到微信朋友圈或微信好友

一、首先创建一个数字签名(keystore文件)这里不再讲述keystore的创建过程&#xff01;二、用keystore给app签名&#xff0c;注意最后如下图所示图中的md5就是 申请apkid时所需的 签名&#xff0c;这里需要注意MD5需要将其中的“&#xff1a;”去掉并将其中的大写字母改为小写三…

android studio开源代码,Android Studio Set of source 代码源集

一、源集1、定义&#xff1a;Android Studio 按逻辑关系将每个模块的源代码和资源进行分组&#xff0c;这个分组叫做源集。2、main Module 源集包括其所有构建变体共用的代码和资源。这句话很关键&#xff0c;意思是&#xff0c;所有的其他构建变体&#xff0c;src/main是其共同…

android nougat和安卓7.1,Android Nougat 7.1.2 先睹为快

Android Nougat 的下一个维护版本 7.1.2 即将发布&#xff01;为了让广大开发者有机会抢先尝鲜&#xff0c;我们从今天开始向已注册 Android Beta 计划、符合条件的设备(包括 Pixel 和 Pixel XL、Nexus 5X、Nexus Player 和 Pixel C 设备)推出公众测试版本。我们还在准备 Nexus…

android app 移植到pc,微软开发新应用把Android app“移植”到Win Phone

依据微软2010年公布在Tweet上的一份专利申请书&#xff0c;微软正在开发一种新服务能够在不同的手机操作系统中“移植”应用和应用数据。这是说Android&#xff0c;iOS应用以后可以跨平台“移植”到 Win Phone Win8系统上&#xff1f;因为Win Phone 著名的“应用问题”&#xf…

鸿蒙系统能否推广,鸿蒙系统凭实力占市场,无需通过禁止安卓系统来推广

有人提议中国应该全面禁用安卓系统&#xff0c;以推广鸿蒙系统(HarmonyOS)&#xff0c;甚至还给出了比如安全等理由。确实有这个必要吗&#xff1f;答案是否定的。一、安卓系统是开源系统&#xff0c;不存在被谷歌完全操控而影响到中国安全的问题。实际上安卓系统诸如碎片化、应…