# 表结构部分
1 drop database if exists `SchoolExam`; 2 create database if not exists `SchoolExam` default character set utf8 collate utf8_unicode_ci; 3 use SchoolExam;
# 创建Student表
1 drop table if exists `Student`; 2 create table if not exists `Student`( 3 ID INT(10) not null auto_increment comment \'学生学号\', 4 `Name` varchar(20) not null comment \'学生姓名\', 5 Sex char(4) comment \'性别\', 6 Birth year comment \'出生日期\', 7 Department varchar(20) not null comment \'院系\', 8 Address varchar(50) comment \'家庭住址\', 9 primary key(ID), 10 unique(ID) 11 )engine=InnoDB charset=utf8;
# 创建Score表
1 drop table if exists `Score`; 2 create table if not exists `Score`( 3 ID int(10) not null auto_increment comment \'成绩编号\', 4 Stu_ID int(10) not null comment \'学生学号\', 5 C_name VARCHAR(20) comment \'科目编号\', 6 Grade int(10) comment \'考试成绩\', 7 primary key(ID), 8 unique(ID) 9 )engine=InnoDB charset=utf8;
# 数据部分
1 insert into Student values(901, \'张老大\', \'男\', 1985, \'计算机系\', \'北京市海淀区\'); 2 insert into Student values(902, \'张老二\', \'男\', 1986, \'中文系\', \'北京市昌平区\'); 3 insert into Student values(903, \'张三\', \'女\', 1990, \'中文系\', \'湖南省永州市\'); 4 insert into Student values(904, \'李四\', \'男\', 1990, \'英语系\', \'辽宁省阜新市\'); 5 insert into Student values(905, \'王五\', \'女\', 1991, \'英语系\', \'福建省厦门市\'); 6 insert into Student values(906, \'王六\', \'男\', 1988, \'计算机系\', \'湖南省衡阳市\'); 7 8 insert into Score values(null, 901, \'计算机\', 98); 9 insert into Score values(null, 901, \'英语\', 80); 10 insert into Score values(null, 902, \'计算机\', 65); 11 insert into Score values(null, 902, \'中文\', 88); 12 insert into Score values(null, 903, \'中文\', 95); 13 insert into Score values(null, 904, \'计算机\', 70); 14 insert into Score values(null, 904, \'英语\', 92); 15 insert into Score values(null, 905, \'英语\', 94); 16 insert into Score values(null, 906, \'计算机\', 90); 17 insert into Score values(null, 906, \'英语\', 85);
#3.查询student表的所有记录
1 select * from Student;
#4.查询student表的第2条到4条记录
1 #limit 1,3--第2条到4条记录 2 select * from Student limit 1,3;
#5.从student表查询所有学生的学号（id）、姓名（name）和院系（department）的信息
1 select `id`,`name`,`department` from Student;
#6.从student表中查询计算机系和英语系的学生的信息
1 select * from Student where `department` in (\'计算机系\',\'英语系\');
#7.从student表中查询年龄18~22岁的学生信息
1 select * from Student where `Birth`<=\'1995\' and `Birth`>=\'1991\'; 2 select id,`name`,sex,(2013-birth) AS age,department,address from Student where (2013-birth) between 18 and 22; 3 #select id,(date_format(from_days(to_days(now()) - to_days(birth)),\'%Y\') + 0) as 年龄 from Student;
#8.从student表中查询每个院系有多少人
select `department`院系, count(`id`)总人数 from Student group by `department`;
#9.从score表中查询每个科目的最高分
select `C_name`科目, max(`Grade`)最高分 from Score group by `C_name`;
#10.查询李四的考试科目（c_name）和考试成绩（grade）
1 select `Name`,`C_name`, `Grade` from Score sc, Student st where sc.Stu_id=st.`Id` and st.`Name`=\'李四\'; 2 #select`C_name`, `Grade` from Score where Stu_id=(select id from Student where `name`=\'李四\');
#11.用连接的方式查询所有学生的信息和考试信息
1 /*select * from Student inner join Score 2 on (Student.`Id`=Score.Stu_id);*/ 3 select student.id,name,sex,birth,department,address,c_name,grade from Student,Score where Student.`Id`=Score.Stu_id;
#12.计算每个学生的总成绩
1 #select `Stu_id`,sum(`Grade`) from Score group by `Stu_id`; 2 select `Stu_id`,`name`,sum(`Grade`) from Student,Score where Student.`Id`=Score.Stu_id group by `Stu_id` ;
#13.计算每个考试科目的平均成绩
select `C_name`科目, avg(`Grade`)平均分 from Score group by `C_name`;
#14.查询计算机成绩低于95的学生信息
select * from Student where `id` in (select `Stu_id` from Score where `C_name`=\'计算机\' and Grade<95);
#15.查询同时参加计算机和英语考试的学生的信息
1 select * from Student where `id` in (select `Stu_id` from Score where `Stu_id` in (select `Stu_id` from Score where `C_name`=\'计算机\') and `C_name`=\'英语\'); 2 /*select a.* from Student a,Score b,Score c 3 where a.id=b.stu_id and b.c_name=\'计算机\' and a.id=c.stu_id and c.c_name=\'英语\';*/
#16.将计算机考试成绩按从高到低进行排序
select * from Score where `C_name`=\'计算机\' order by Grade desc;
#17.从student表和score表中查询出学生的学号，然后合并查询结果
1 #union--合并字段，去掉重复 2 /*select * from Student 3 left join Score 4 on(Student.`id`=Score.Stu_id);*/ 5 select id from Student union select stu_id from Score;
#18.查询姓张或者姓王的同学的姓名、院系和考试科目及成绩
1 /*select `Name`姓名, Department 院系,C_name 考试科目,Grade 成绩 from Student 2 left join Score 3 on(Student.`id`=Score.Stu_id) 4 where `Name` like \'张%\' or `Name` like \'王%\';*/ 5 select `Name`姓名, Department 院系,C_name 考试科目,Grade 成绩 from Student,Score 6 where (`Name` like \'张%\' or `Name` like \'王%\') and Student.`id`=Score.Stu_id;
#19.查询都是湖南的学生的姓名、年龄、院系和考试科目及成绩
1 /*select `Name`姓名, Department 院系,C_name 考试科目,Grade 成绩 from Student 2 left join Score 3 on(Student.`id`=Score.Stu_id) 4 where `Address` like \'湖南%\' ;*/ 5 select `Name`姓名,(select timestampdiff(year,Birth,now())) as 年龄, Department 院系,C_name 考试科目,Grade 成绩 from Student,Score 6 where `Address` like \'湖南%\' and Student.`id`=Score.Stu_id;
#20.统计分数低于60分，60分——70分，70分——80分，大于80分的学生人数。
1 #select stu_id,count(stu_id) from Score where Grade between 70 and 80 group by stu_id; 2 select 3 count(case when Grade<60 then 1 end ) as \'60分以下人数\', 4 count(case when Grade>=60 and Grade<70 then 1 end ) as \'60~70分人数\', 5 count(case when Grade>=70 and Grade<80 then 1 end ) as \'70~80分人数\', 6 count(case when Grade>=80 then 1 end ) as \'80分以上人数\' 7 from Score;
#21.统计平均成绩大于90分的学生，显示学号、姓名、总平均成绩。
1 select `Stu_id`,`name`,avg(Grade) from Score,Student where Student.`id`=Score.Stu_id group by `Stu_id`,`name` having avg(Grade)>90; 2 /*SELECT `Stu_id`,`name`,avg(Grade) 3 FROM Score,Student 4 WHERE Student.`id`=Score.Stu_id 5 GROUP BY `Stu_id`,`name` 6 HAVING AVG(GRADE)>=90;*/