text: create table if not exists users
  (
      id       bigserial not null
          constraint users_pkey
              primary key,
      username text
          constraint users_username_key
              unique,
      password bytea
  );
  
  create table computers
  (
      id      serial                                                    not null
          constraint computers_pk
              primary key,
      user_id integer                                                   not null
          constraint computers_users_id_fk
              references users
              on update cascade on delete cascade,
      name    varchar(255)                                              not null,
      mac     varchar(17)                                               not null,
      ip      varchar(100) default '255.255.255.255'::character varying not null,
      port    integer      default 9                                    not null,
      constraint computers_pk_2
          unique (user_id, name)
  );
  