MySQL查询语句

2022-12-18 13:27:07

MySQL经典查询

建表

#建学生信息表student
create table student
(
sno varchar(20) not null primary key,
sname varchar(20) not null,
ssex varchar(20) not null,
sbirthday datetime,
class varchar(20)
);

#建立教师表
create table teacher
(
tno varchar(20) not null primary key,
tname varchar(20) not null,
tsex varchar(20) not null,
tbirthday datetime,
prof varchar(20),
depart varchar(20) not null
);

#建立课程表course
create table course
(
cno varchar(20) not null primary key,
cname varchar(20) not null,
tno varchar(20) not null,
foreign key(tno) references teacher(tno)
);

#建立成绩表
create table score
(
sno varchar(20) not null primary key,
foreign key(sno) references student(sno),
cno varchar(20) not null,
foreign key(cno) references course(cno),
degree decimal
);

#建立grade表
create table grade(
low int,
upp int,
grade char(1)
);

插入数据

#建立成绩表
insert into student values('108','曾华','男','1977-09-01','95033');
insert into student values('105','匡明','男','1975-10-02','95031');
insert into student values('107','王丽','女','1976-01-23','95033');
insert into student values('101','李军','男','1976-02-20','95033');
insert into student values('109','王芳','女','1975-02-10','95031');
insert into student values('103','陆君','男','1974-06-03','95031');

#添加教师表
insert into teacher values('804','李诚','男','1958-12-02','副教授','计算机系');
insert into teacher values('856','张旭','男','1969-03-12','讲师','电子工程系');
insert into teacher values('825','王萍','女','1972-05-05','助教','计算机系');
insert into teacher values('831','刘冰','女','1977-08-14','助教','电子工程系');

#添加课程表
insert into course values('3-105','计算机导论','825');
insert into course values('3-245','操作系统','804');
insert into course values('6-166','数字电路','856');
insert into course values('9-888','高等数学','831');

#添加成绩表
insert into score values('103','3-245','86');
insert into score values('105','3-245','75');
insert into score values('109','3-245','68');
insert into score values('103','3-105','92');
insert into score values('105','3-105','88');
insert into score values('109','3-105','76');
insert into score values('103','3-105','64');
insert into score values('105','3-105','91');
insert into score values('109','3-105','78');
insert into score values('103','6-166','85');
insert into score values('105','6-166','79');
insert into score values('109','6-166','81');

#添加grade表
insert into grade values(90,100,'A');
insert into grade values(80,89,'B');
insert into grade values(70,79,'C');
insert into grade values(60,69,'D');
insert into grade values(0,59,'E');

查询Student表中的所有记录的Sname、Ssex和Class列，并分页一页两条内容，显示第三页内容。
select sname,ssex,class from student LIMIT 4,2;
查询教师所有的单位即不重复的Depart列。
SELECT DISTINCT depart from teacher;
查询Student表的所有记录。
SELECT * from student;
查询Score表中成绩在60到80之间的所有记录。
SELECT * from score where degree BETWEEN 60 and 80;
查询Score表中成绩为85，86或88的记录。
SELECT * from score where degree in(85,86,88);
查询Student表中“95031”班或性别为“女”的同学记录。
SELECT * from student WHERE class='95031' or ssex='女';
以Class降序查询Student表的所有记录。
SELECT * from student ORDER BY class DESC;
以Cno升序、Degree降序查询Score表的所有记录。
SELECT * from score ORDER BY cno,degree desc;
查询“95031”班的学生人数。
SELECT count(sno) from student where class='95031';
查询Score表中的最高分的学生学号和课程号。（子查询）
SELECT sno,cno from score where degree=(SELECT max(degree) FROM score);
查询每门课的平均成绩。
SELECT cno,avg(degree) from score GROUP BY cno;
查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。
SELECT avg(degree) from score WHERE cno like '3%' GROUP BY cno HAVING count(sno)>=5;
查询分数大于70，小于90的Sno列。
SELECT sno,degree from score WHERE degree>70 and degree<90;
查询所有学生的Sname、Cno和Degree列。
SELECT sname,cno,degree from student LEFT JOIN score on student.sno=score.sno;
查询所有学生的Sno、Cname和Degree列。
SELECT student.sno,cname,degree from student LEFT JOIN score on student.sno=score.sno LEFT JOIN course on score.cno=course.cno;
查询所有学生的Sname、Cname和Degree列。
SELECT student.sname,cname,degree from student LEFT JOIN score on student.sno=score.sno LEFT JOIN course on score.cno=course.cno;
查询“95033”班学生的平均分。
SELECT avg(degree) from score,student where student.class='95033';
查询所有同学的Sno、Cno和grade列。
SELECT score.sno,cno,grade.grade from score LEFT JOIN grade on score.degree BETWEEN grade.low and grade.upp;
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。
SELECT * from score WHERE degree>(SELECT degree from score where sno='109') and cno='3-105';

选了多门课程并且是这个课程下不是最高分的学生信息

    #数据源 score 
	#1.选了多个课程的学生
	SELECT sno from score GROUP BY sno HAVING count(cno)>1;
	#2.每门课的最高成绩
	SELECT cno,MAX(degree) from score GROUP BY cno;
	#链接1.2.两表，需要创建链接变量
	
	#改编1.表，构建选了多个课程的适合链接的表
	SELECT * from score WHERE sno in(SELECT sno from score GROUP BY sno HAVING count(cno)>1);
	#链接两表
	SELECT * from (SELECT * from score WHERE sno in(SELECT sno from score GROUP BY sno HAVING count(cno)>1) ) s1 INNER JOIN (SELECT cno,MAX(degree) max from score GROUP BY cno) s2 on s1.cno=s2.cno and s1.degree < s2.max;

查询成绩高于学号为“109”且课程号为“3-105”的成绩的所有记录。
SELECT * from score where degree> (SELECT degree from score where sno='109'and cno='3-105');
查询和学号为108、101的同学同年出生的所有学生的Sno、Sname和Sbirthday列。
SELECT sno,sname,sbirthday from student where year(sbirthday)in (SELECT year(sbirthday) from student where sno='108' or sno='101');
查询“张旭“教师任课的学生成绩。
SELECT degree from teacher,course,score where teacher.tno=course.tno and course.cno=score.cno and teacher.tname='张旭' ;

查询选修某课程的同学人数多于5人的教师姓名。

#数据源score,teacher,course
#大于五人的科目
SELECT cno from score GROUP BY cno HAVING count(sno)>5;
SELECT tname from  teacher,course c,(SELECT cno from score GROUP BY cno HAVING count(sno)>5) cn where cn.cno=c.cno and c.tno=teacher.tno;

查询95033班和95031班全体学生的记录。
SELECT * from student where class in ('95033','95031');
查询存在有85分以上成绩的课程Cno.
SELECT cno from score where degree>85;

查询出“计算机系“教师所教课程的成绩表。

#数据源teacher course score
SELECT  degree from teacher LEFT JOIN course on teacher.tno=course.tno LEFT JOIN score on course.cno=score.cno where depart='计算机系';

查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。

SELECT tname,prof from teacher WHERE depart='计算机系' and prof not in(SELECT prof from teacher WHERE depart='电子工程系')
UNION
SELECT tname,prof from teacher WHERE depart='电子工程系'and prof not in(SELECT prof from teacher WHERE depart='计算机系');

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。

#any 大于集合最小值
SELECT cno,sno,degree from score where degree >any(SELECT degree from score where cno='3-245') and cno='3-105' ORDER BY degree desc;

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.

#all 大于集合最大值
SELECT cno,sno,degree from score where degree >all(SELECT degree from score where cno='3-245');

查询所有教师和同学的name、sex和birthday.

SELECT sname,ssex,sbirthday from student 
UNION
SELECT tname,tsex,tbirthday from teacher;

查询所有“女”教师和“女”同学的name、sex和birthday.

SELECT sname,ssex,sbirthday from student where ssex='女' 
UNION
SELECT tname,tsex,tbirthday from teacher where tsex='女';

查询成绩比该课程平均成绩低的同学的成绩表。

SELECT avg(degree) from score GROUP BY cno;
SELECT degree from score,(SELECT cno,avg(degree) avg from score GROUP BY cno) avg_d where score.cno=avg_d.cno and score.degree<avg_d.avg;

查询所有任课教师的Tname和Depart.
SELECT tname,depart from teacher where teacher.tno in(SELECT course.tno from course);
查询所有未讲课的教师的Tname和Depart.
SELECT tname,depart from teacher where teacher.tno not in(SELECT course.tno from course);
查询至少有2名男生的班号。
SELECT class from student where ssex='男' GROUP BY class HAVING count(sno)>1 ;
查询Student表中不姓“王”的同学记录。
SELECT * from student where sname not like '王%';
查询Student表中每个学生的姓名和年龄。
SELECT sname,YEAR(now())-YEAR(sbirthday) age from student ;
查询Student表中最大和最小的Sbirthday日期值。
SELECT date(max(sbirthday)) max,date(min(sbirthday)) min from student ;
以班号和年龄从大到小的顺序查询Student表中的全部记录。
SELECT * from student ORDER BY class desc,sbirthday;
查询“男”教师及其所上的课程。
SELECT * from teacher left join course on teacher.tno=course.tno WHERE tsex='男';

查询最高分同学的Sno、Cno和Degree列。

SELECT max(degree) from score ;
SELECT * from score where degree=(SELECT max(degree) from score );

查询和“李军”同性别的所有同学的Sname.
SELECT sname from student where ssex=(SELECT ssex from student where sname='李军')and sname!='李军';
查询和“李军”同性别并同班的同学Sname.
SELECT sname from student where ssex=(SELECT ssex from student where sname='李军') and class=(SELECT class from student where sname='李军') and sname!='李军'

查询所有选修“计算机导论”课程的“男”同学的成绩表。

SELECT degree from score,course,student where student.sno=score.sno and score.cno=course.cno and student.ssex='男' and course.cname='计算机导论';```

码农公寓

MySQL经典查询

建表

插入数据

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