MySQL 8.0

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select version();

drop table if exists obj;
create table obj (
  id int not null primary key auto_increment,
  name varchar(20),
  objectType enum("type1", "type2")
);

drop table if exists objExt1;
create table objExt1 (
  id int not null primary key,
  color varchar(20),
  foreign key (id) references obj(id) on delete cascade
);

drop table if exists objExt2;
create table objExt2 (
  id int not null primary key,
  weight int,
  foreign key (id) references obj(id) on delete cascade
);


select * from obj as o inner join objExt1 as o1 on o.id = o1.id;
insert into obj (name, objectType) values ('objA type 1', "type1");
insert into objExt1 (id, color) values (1, 'red');

select * from obj as o inner join objExt2 as o2 on o.id = o2.id;
insert into obj (name, objectType) values ('objA type 2', "type2");
insert into objExt2 (id, weight) values (2, 300);


version()


8.0.27


select * from obj as o inner join objExt1 as o1 on o.id = o1.id;


id
name
objectType
id
color


1
objA type 1
type1
1
red


select * from obj as o inner join objExt2 as o2 on o.id = o2.id;


id
name
objectType
id
weight


2
objA type 2
type2
2
300