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Today, the editor will share with you the relevant knowledge points about how MySQL creates three relationship tables. The content is detailed and the logic is clear. I believe most people still know too much about this knowledge, so share this article for your reference. I hope you can get something after reading this article. Let's take a look at it.

1. Create a student table create table tbl_stu (id int not null primary key auto_increment,name varchar (45) not null) engine=innodb default charset=utf8

two。 Create the chart create table tbl_sub (id int not null primary key auto_increment,subject varchar (45) not null) engine=innodb default charset=utf8

3. Create a score table create table tbl_scores (id int not null primary key auto_increment,stu_id int,sub_id intscore decimal (5Power2), constraint sco_stu foreign key (stu_id) references tbl_stu (id), constraint sco_sub foreign key (sub_id) references tbl_sub (id))

4. Insert data insert into tbl_stu values (0, Xiao Wang); insert into tbl_stu values (0, Xiao Song); insert into tbl_stu values (0, Xiao Li); insert into tbl_sub values (0, "Chinese"); insert into tbl_sub values (0, "Mathematics"); insert into tbl_sub values (0, "English"); insert into tbl_scores values Insert into tbl_scores values, etc. Query all scores select s3.namejournal s2.scotjournal s1.score from tbl_scores as s1inner join tbl_sub as S2 on s1.sub_id = s2.idinner join tbl_stu as S3 on s1.sub_id = s3.id

6. Query the average score of the students select s3.namemagint avg (s1.score) from tbl_scores as s1inner join tbl_stu as S3 on s1.sub_id = s3.idgroup by s3.name

7. Total score ranking select s3.Name as s from tbl_scores as s1inner join tbl_stu as S3 on s1.stu_id = s3.idgroup by s3.name order by s desc

These are all the contents of the article "how to create three relationship tables by MySQL". Thank you for reading! I believe you will gain a lot after reading this article. The editor will update different knowledge for you every day. If you want to learn more knowledge, please pay attention to the industry information channel.

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