數(shù)據(jù)庫多表查詢作業(yè)

創(chuàng)建數(shù)據(jù)庫

插入數(shù)據(jù)

mysql> insert into student values(901,'張老大','男',1985,'計(jì)算機(jī)系','北京市海淀區(qū)'),
    -> (902,'張老二','男',1986,'中文系','北京市昌平市'),
    -> (903,'張三','女',1990,'中文系','湖南省永州市'),                                           -> (904,'李四','男',1990,'英語系','遼寧省阜新市'),                                           -> (905,'王五','女',1991,'英語系','福建省廈門市'),
    -> (906,'王六','男',1988,'計(jì)算機(jī)系','湖南省衡陽市');

mysql> insert into score values(null,901,'計(jì)算機(jī)',98),
    -> (null,901,'英語',80),
    -> (null,902,'計(jì)算機(jī)',65),
    -> (null,902,'中文',88),
    -> (null,903,'中文',95),
    -> (null,904,'計(jì)算機(jī)',70),
    -> (null,904,'英語',92),
    -> (null,905,'英語',94),
    -> (null,906,'計(jì)算機(jī)',90),
    -> (null,906,'英語',85);

1.查詢student表的所有記錄

mysql> select * from student;

2.查詢student表的第2條到4條記錄

mysql> select * from student limit 1,3;

3.從student表查詢所有學(xué)生的學(xué)號(hào)（id）、姓名
（name）和院系（department）的信息

mysql> select id as 學(xué)號(hào),name as 姓名,department as 院系 from student;

4.從student表中查詢計(jì)算機(jī)系和英語系的學(xué)生的信息

mysql> select * from student where department='計(jì)算機(jī)系' or department='英語系';

5.從student表中查詢年齡18~22歲的學(xué)生信息

mysql> select *,year(curdate())-birth as age from student where year(curdate())-birth between 18 and 22;

6.從student表中查詢每個(gè)院系有多少人

mysql> select department as 院系,count(*) as 人數(shù) from student group by department;

7.從score表中查詢每個(gè)科目的最高分

mysql> select c_name as 科目,max(grade) as 最高分 from score group by c_name;

8.查詢李四的考試科目（c_name）和考試成績（grade）

mysql> select name as 姓名,c_name as 科目,grade as 成績 from student
    -> inner join score on student.id=score.stu_id
    -> where name='李四';

9.用連接的方式查詢所有學(xué)生的信息和考試信息

mysql> select * from student iudent inner join score on student.id=score.stu_id;

10.計(jì)算每個(gè)學(xué)生的總成績

mysql> select name as 姓名,sum(grade) as 總成績 from student
    -> inner join score on student.id=score.stu_id
    -> group by name;

11.計(jì)算每個(gè)考試科目的平均成績

mysql> select avg(grade) from score group by c_name;

12.查詢計(jì)算機(jī)成績低于95的學(xué)生信息

mysql> select * from student
    -> inner join (select stu_id,c_name,grade from score where grade<95 and c_name='計(jì)算機(jī)') as stu
    -> on student.id=stu.stu_id;

13.查詢同時(shí)參加計(jì)算機(jī)和英語考試的學(xué)生的信息

獲取同時(shí)考計(jì)算機(jī)和英語的學(xué)生ID

select * from score where c_name='英語') as sc2 where sc1.stu_id=sc2.stu_id

根據(jù)ID獲取學(xué)生信息

mysql> select * from student inner join (select sc1.stu_id from (select * from score where c_name='計(jì)算機(jī)') as sc1,(select * from score where c_name='英語') as sc2 where sc1.stu_id=sc2.stu_id) as sc on student.id=sc.stu_id;

14.將計(jì)算機(jī)考試成績按從高到低進(jìn)行排序

mysql> select * from score where c_name='計(jì)算機(jī)' order by grade desc;

15.從student表和score表中查詢出學(xué)生的學(xué)號(hào)，然后合并查詢結(jié)果

mysql> select student.id,score.stu_id from student inner join (select distinct stu_id from score) as score on student.id=score.stu_id;

16.查詢姓張或者姓王的同學(xué)的姓名、院系和考試科目及成績

mysql> select stu.name as 姓名, stu.department as 院系, score.c_name as 科目,score.grade as  成績
    -> from score inner join
    -> (select * from student where name like '張%' or name like '王') as stu
    -> on score.stu_id=stu.id;

17.查詢都是湖南的學(xué)生的姓名、年齡、院系和考試科目及成績

mysql> select stu.name as 姓名,year(curdate())-stu.birth as age,stu.department as 院系,score.c_name as 科目,score.grade as 成績
    -> from score
    -> inner join
    -> (select * from student where address like '%湖南%') as stu
    -> on score.stu_id=stu.id;

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