text: create table if not exists account (
    _id    serial primary key,
    _name  text not null,
    _phone text not null,
    unique (_name, _phone)
    );
  
  create table if not exists seat (
    _id       serial primary key,
    _row      int not null,
    _column   int not null,
    _price    int not null,
    _owner_id int references account(_id) default null,
    unique (_row, _column)
    );
  
  create table if not exists payment (
    _id      serial primary key,
    _amount  int  not null,
    _from_id int  not null references account(_id),
    _comment text not null
    );