text: create table countries (
      id serial primary key,
      name text not null unique,
      code text not null unique
  );
  
  create table companies (
      id serial primary key,
      name text not null unique,
      inn text not null unique,
      id_country integer not null references countries
  );
  
  create table a (
      id serial primary key,
      b text,
      a text
  );
  
  create table b (
      id serial primary key,
      a text,
      b text
  );
  
  CREATE SCHEMA test;
  
  create table test.test (
      id serial primary key,
      test text
  );
  
  create table test.companies (
      id serial primary key,
      is_test boolean
  );