create table teachers (
id int primary key not null,
name varchar(20) not null
);
create table office (
id int primary key references teachers (id),
floor smallint check (floor > 0 and floor <= 10),
size smallint check (size > 0)
);
alter table teachers
add constraint fk_uq1_teachers_office
foreign key (id) references office (id) deferrable initially deferred;
Error: (1:1) Reference with the same endpoints already exists: “teachers”(“id”) references “office”(“id”)