diff --git "a/23 \351\273\204\346\265\251\344\270\234/20230301 MySQL\345\207\275\346\225\260\345\222\214\350\201\224\345\220\210\346\237\245\350\257\242\345\222\214\345\205\263\350\201\224\346\237\245\350\257\242.md" "b/23 \351\273\204\346\265\251\344\270\234/20230301 MySQL\345\207\275\346\225\260\345\222\214\350\201\224\345\220\210\346\237\245\350\257\242\345\222\214\345\205\263\350\201\224\346\237\245\350\257\242.md"
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@@ -0,0 +1,238 @@
+# 作业
+
+### 1 建表
+
+```mysql
+#建表
+REATE table Student (Sno varchar(20) PRIMARY KEY,Sname varchar(20) not null, Ssex varchar(20) not null,Sbirthday datetime,Class varchar(20));
+create table Course(Cno varchar(20) PRIMARY KEY, Cname varchar(20) not null,Tno varchar(20) not null);
+create table Score(Sno varchar(20) not null,Cno varchar(20) not null,Degree Decimal(4,1),PRIMARY KEY (Sno,Cno));
+create table Teacher(Tno varchar(20) PRIMARY KEY,Tname varchar(20) not null,Tsex varchar(20) not null,Tbirthday datetime,Prof varchar(20),Depart varchar(20) not null);
+```
+
+```mysql
+#建外键
+alter table Course add foreign key (Tno) REFERENCES Teacher (Tno);
+alter table Score add foreign key (Sno) REFERENCES Student (Sno);
+alter table Score add foreign key (Cno) REFERENCES Course (Cno);
+```
+
+-- 3.	数据库中的数据:
+1,查询所有学生，都学了哪些课程，要显示学生信息和课程信息
+
+```mysql
+Select a.*,c.Cname,c.Cno from Student a left join score b on a.Sno = b.Sno left join course c on b.Cno = c.Cno
+```
+
+ 2，查询没有学生的教师的所有信息
+
+```mysql
+select a.*,b.* from teacher a LEFT JOIN course b on a.tno = b.tno left JOIN score c on b.Cno= c.Cno where b.Cno not in (select Cno from score);
+```
+
+### 2 插入数据
+
+-- 表（一）Student
+-- Sno	Sname	Ssex	Sbirthday	class
+-- 108	曾华	男	1977-9-1	95033
+-- 105	匡明	男	1975-10-2	95031
+-- 107	王丽	女	1976-1-23	95033
+-- 101	李军	男	1976-2-20	95033
+-- 109	王芳	女	1975-2-10	95031
+-- 103	陆君	男	1974-6-3	95031
+
+```mysql
+insert into Student values (108,'曾华','男','1977-9-1',95033),(105,'匡明','男','1975-10-2','95031'),(107,'王丽','女','1976-1-23',95033),(101,'李军','男','1976-2-20',95033),(109,'王芳','女','1975-2-10',95031),(103,'陆君','男','1974-6-3',95031);
+#第一个添加
+```
+
+-- 表（二）Course
+-- Cno	Cname	Tno
+-- 3-105	计算机导论	825
+-- 3-245	操作系统	804
+-- 6-166	数字电路	856
+-- 9-888	高等数学	831
+
+```mysql
+insert into Course values('3-105','计算机导论',825),('3-245','操作系统',804),('6-166','数字电路',856),('9-888','高等数学',831);
+```
+
+-- 表（三）Score
+-- Sno	Cno	Degree
+-- 103	3-245	86
+-- 105	3-245	75
+-- 109	3-245	68
+-- 103	3-105	92
+-- 105	3-105	88
+-- 109	3-105	76
+-- 101	3-105	64
+-- 107	3-105	91
+-- 108	3-105	78
+-- 101	6-166	85
+-- 107	6-166	79
+-- 108	6-166	81
+
+```mysql
+insert into Score values(103,'3-245',86),(105,'3-245',75),(109,'3-245',68),(103,'3-105',92),(105,'3-105',88),(109,'3-105',76),(101,'3-105',64),(107,'3-105',91),(108,'3-105',78),(101,'6-166',85),(107,'6-166',79),(108,'6-166',81);
+```
+
+-- 表（四）Teacher
+-- Tno	Tname	Tsex	Tbirthday	Prof	Depart
+-- 804	李诚	男	1958-12-2	副教授	计算机系
+-- 856	张旭	男	1969-3-12	讲师	电子工程系
+-- 825	王萍	女	1972-5-5	助教	计算机系
+-- 831	刘冰	女	1977-8-14	助教	电子工程系
+
+```mysql
+insert into Teacher values (804,'李诚','男','1958-12-2','副教授','计算机系'),(856,'张旭','男','1969-3-12','讲师','电子工程系'),(825,'王萍','女','1972-5-5','助教','计算机系'),(831,'刘冰','女','1977-8-14','助教','电子工程系');#第二个添加
+```
+
+### 3 查询
+
+-- ①　查询Score表中的最高分的学生学号和课程号。
+
+```mysql
+select Cno,Sno from Score where Degree=(select MAX(Degree) from Score);
+```
+
+-- ②　查询所有学生的Sname、Cno和Degree列。
+
+```mysql
+select Sname,Cno,Degree from Student a LEFT JOIN Score b on a.Sno=b.Sno;
+```
+
+ 
+
+-- ③　查询所有学生的Sno、Cname和Degree列。
+
+```mysql
+select Sno,Cname,Degree from Score a LEFT JOIN Course b on a.Cno=b.Cno;
+```
+
+-- ④　查询所有学生的Sname、Cname和Degree列。
+
+```mysql
+select b.Sname,c.Cname,Degree from Score a LEFT JOIN Student b on a.Sno=b.Sno left join Course c on a.Cno=c.Cno;
+```
+
+-- ⑤　查询“95033”班学生的平均分。
+
+```mysql
+select avg(Degree) from score a left JOIN student b on a.Sno = b.Sno where b.Class = 95033;
+```
+
+-- ⑥　查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。
+
+```mysql
+select * from score a left join student b on a.Sno = b.Sno where a.Cno = '3-105' and degree>(select degree from score where Cno = '3-105'and Sno = 109) ;
+```
+
+-- ⑦　查询score中选学多门课程的同学中分数为非最高分成绩的记录。
+
+```mysql
+select * from score a WHERE a.degree not in (SELECT max(b.Degree) from score b where a.Cno = b.cno);
+```
+
+-- ⑧　查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。
+
+```mysql
+select * from score where Cno = '3-105' and degree > (select degree from score where Sno = 109 and Cno = '3-105');
+```
+
+#分组函数不能用于where语句
+
+```mysql
+select * from score a left JOIN student b on a.Sno = b.Sno where degree>(select Degree from score where Sno=109 and Cno = '3-105');
+```
+
+-- ⑨　查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。
+
+```mysql
+select Sno,Sname,Sbirthday from student where YEAR(Sbirthday) = (select YEAR(Sbirthday) from student where Sno = 108);
+```
+
+-- ⑩　查询“张旭“教师任课的学生成绩。
+
+```mysql
+select Tname,degree from score a LEFT JOIN course b on a.Cno = b.Cno LEFT JOIN teacher c on b.Tno = c.Tno where c.Tname = (select Tname from teacher where Tname = '张旭');
+```
+
+-- 11　查询选修某课程的同学人数多于5人的教师姓名。
+
+```mysql
+#   HAVING语句用于分组后筛选
+SELECT Tname FROM teacher WHERE Tno = ( SELECT tno FROM course WHERE cno =( SELECT cno FROM score GROUP BY cno HAVING COUNT ( Cno )> 5 ));
+```
+
+-- 12　查询出“计算机系“教师所教课程的成绩表。
+
+```mysql
+SELECT Tname,a.Tno,b.Cno,c.Sno,c.Degree FROM teacher a LEFT JOIN course b ON a.Tno = b.Tno LEFT JOIN score c ON b.Cno = c.Cno WHERE a.depart = '计算机系';
+```
+
+-- 13　查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。
+
+```mysql
+SELECT Tname,Prof FROM teacher WHERE prof not in (select prof from teacher where Depart = '电子工程系') AND Depart = '计算机系';
+```
+
+-- 14　查询选修编号为“3-105“课程且成绩至少高于选修编号为“3-245”的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。
+
+```mysql
+select Cno,Sno,Degree from score where Cno = '3-105' AND Degree> ANY (select degree from score where Cno = '3-245') ORDER BY Degree;
+```
+
+-- 15　查询选修编号为“3-105”且成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree.
+
+```mysql
+select Cno,Sno,Degree from score where Cno = '3-105' and Degree > all (select degree from score where Cno = '3-245');
+```
+
+-- 16　查询成绩比该课程平均成绩低的同学的成绩表。
+
+```mysql
+select * FROM score a where Degree < (select avg(degree)from score b where a.Cno = b.Cno);
+```
+
+-- 17　查询所有任课教师的Tname和Depart.
+
+```mysql
+select Tname,Depart from teacher;
+```
+
+-- 18　查询所有未讲课的教师的Tname和Depart.
+
+```mysql
+select Tname,Depart from teacher a LEFT JOIN course b on a.tno = b.tno left JOIN score c on b.Cno= c.Cno where b.Cno not in (select Cno from score);
+```
+
+-- 19　查询“男”教师及其所上的课程。
+
+```mysql
+select b.Cname,a.Tsex from teacher a LEFT JOIN course b on a.Tno=b.Tno where a.Tsex='男' ;
+```
+
+-- 20　查询最高分同学的Sno、Cno和Degree列。
+
+```mysql
+select a.Sno,a.Cno,a.Degree from score a where a.degree = (select MAX(b.degree) from score b where a.Cno=b.Cno);
+```
+
+-- 21　查询和“李军”同性别的所有同学的Sname.
+
+```mysql
+select Sname,Ssex from student where Ssex = (select Ssex from student where Sname = '李军');
+```
+
+-- 22　查询和“李军”同性别并同班的同学Sname.
+
+```mysql
+select Sname,Ssex,Class from student where Ssex = (select Ssex from student where Sname = '李军') and Class = (select Class from student where Sname = '李军');
+```
+
+-- 23　查询所有选修“计算机导论”课程的“男”同学的成绩表。
+
+```mysql
+select c.Cname,Sname,b.Ssex,a.Degree FROM score a LEFT JOIN student b on a.Sno = b.Sno left JOIN course c on a.Cno=c.Cno where b.Ssex = '男' and c.Cname = '计算机导论'
+```
+
diff --git "a/23 \351\273\204\346\265\251\344\270\234/20230307 MySQL\346\237\245\350\257\242\347\273\274\345\220\210\344\275\234\344\270\232.md" "b/23 \351\273\204\346\265\251\344\270\234/20230307 MySQL\346\237\245\350\257\242\347\273\274\345\220\210\344\275\234\344\270\232.md"
new file mode 100644
index 0000000000000000000000000000000000000000..6e06a54b37afda754bfb36992565f73ddedc0ac9
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+++ "b/23 \351\273\204\346\265\251\344\270\234/20230307 MySQL\346\237\245\350\257\242\347\273\274\345\220\210\344\275\234\344\270\232.md"	
@@ -0,0 +1,61 @@
+## 作业
+
+### 1建表
+
+```MySQL
+create database homework charset utf8;
+use homework;
+CREATE table stuinfo(stuNO char(5),stuName varchar(30) not NULL,stuSex char,stuAge char(2),stuAddress varchar(20),stuSeat int, primary key (stuNO),unique key (stuSeat));
+CREATE table stuExam (examNO int not NULL,stuNO char(5),writtenExam int not null default 0,labExam int not null default 0,primary key (stuNO),UNIQUE key (examNO));
+create table stuMarks (examNO int not null,stuID char(5) not null,score int not null DEFAULT 0 , UNIQUE key (examNo));
+```
+
+### 2查询
+
+```MySQL
+insert into stuinfo values ('s2501','张秋利','男',20,'美国硅谷',1),('s2502','李斯文','女',18,'湖北武汉',2),('s2503','马文才','男',18,'湖南长沙',3),('s2504','欧阳俊雄','女',21,'湖北武汉',4),('s2505','梅超风','男',20,'湖北武汉',5),('s2506','陈旋风','男',19,'美国硅谷',6);
+INSERT into stuExam values (1,'s2501',50,70),(2,'s2502',60,65),(3,'s2503',86,70),(4,'s2504',40,80),(5,'s2505',70,85),(6,'s2506',85,90);
+insert into stuMarks values(1,'s2501',88),(2,'s2501',92),(3,'s2501',53),(4,'s2502',60),(5,'s2502',99),(6,'s2503',82);
+-- 1.查询出年龄比班上平均年龄大的学生的信息
+select * from stuinfo where stuAge > (select avg(stuAge) from stuinfo )
+-- 2.查询出每个学生的学号，姓名，性别和选修课程的最高分（stuMarks）
+--  sutNO,stuName,stuSex,MAX(score)
+select a.stuNO,a.stuName,a.stuSex,b.score from stuinfo a LEFT JOIN (select stuID,score from stuMarks c where  score = (select max(score) from stuMarks d where c.stuID = d.stuID))b on a.stuNO = b.stuID where b.score is not null;
+-- 3.查询出每个学生的学号，姓名，性别和考试平均分（stuExam）
+-- stuNO,stuName,stuSex,avg(writeemExame+labExame)
+select a.stuNO,a.stuName,a.stuSex,b.`avg` from stuinfo a
+left join
+(select c.stuNO,((c.writtenExam+c.labExam)/2) as `avg` from stuexam c) b
+on a.stuNO = b.stuNO
+-- 4.查询性别是男并且年龄大于等于20的学生的信息(用两种方法实现：普通查询和子查询)
+select * from stuinfo where stuAge >= 20 and stuSex = '男';
+select * from stuinfo where stuNO = any(select stuNO from stuinfo where stuAge >= 20 and stuSex = '男');
+-- 5.查询出年龄比所有男生年龄都大的女生的信息
+select *from stuinfo where stuSex = '女' and stuAge > (select max(stuAge) from stuinfo where stuSex ='男');
+-- 6.查询出所有选修课程都及格的学生的信息   （stuMarks）
+select * from stuinfo a left join stumarks b on a.stuNO=b.stuID where b.score >= 60;
+
+-- 7.查询出参加考试的学生的信息（用表连接，in二种方法做）（stuMarks）
+select a.* from stuinfo a left join stumarks b on a.stuNO = b.stuID where score is not NULL;
+select * from stuinfo where stuNO in (select stuID from stumarks where score is not null);
+-- 8.查询出没有参加考试的学生的信息（用表连接，in二种方法做）（stuMarks）
+select a.* from stuinfo a left join stumarks b on a.stuNO = b.stuID where score is NULL;
+select * from stuinfo where stuNO not in (select stuID from stumarks where score is not null);
+-- 9.将有一门成绩成绩大于90分的学生的基本信息查询出来（stuMarks）
+select a.* from stuinfo a left join stumarks b on a.stuNO = b.stuID where b.score>90;
+-- 10.查询出平均成绩在80分以上的学生的基本信息（stuMarks）
+select * from stuinfo a LEFT JOIN
+(select stuID,AVG(score) c from stuMarks GROUP BY stuID having AVG(score)>80)b
+on a.stuNO = b.stuID where b.c is not null;
+
+-- 11.查询出某同学所有考试成绩比“张秋利”同学所有分数都高的学生基本信息（stuMarks）
+select DISTINCT a.* from stuinfo a left JOIN stumarks b on a.stuNo=b.stuID where b.score > all(SELECT score from stumarks c LEFT JOIN stuinfo d ON c.stuID = d.stuNO where d.`stuName`='张秋利' ) and stuName !=  '张秋利'
+-- 12.查询出某同学所有考试成绩只需要比“张秋利”同学某个分数高的学生基本信息（stuMarks）
+select DISTINCT a.* from stumarks b RIGHT JOIN stuinfo a on a.stuNo=b.stuID where b.score > any(SELECT score from stumarks c LEFT JOIN stuinfo d ON c.stuID = d.stuNO where d.`stuName`='张秋利' ) and a.stuName != '张秋利' 
+
+-- 13.查询班上比所有男生年龄都要大的女生的信息
+select *from stuinfo where stuSex = '女' and stuAge > (select max(stuAge) from stuinfo where stuSex ='男');
+-- 14.查询出只是比某个男生年龄大的女生的信息
+select *from stuinfo where stuSex = '女' and stuAge > any(select stuAge from stuinfo where stuSex ='男');
+```
+