text: CREATE TABLE Region(
      -- ...
      id integer primary key not null, 
      name varchar(127) not null,
      -- ..
      constraint region_idx1 unique (name)
  );
  
  CREATE TABLE City(
      -- ...
      id integer primary key not null, 
      name varchar(127) not null,
      region_id integer not null,    
      -- ..
      -- constraint city_idx1 unique (name),    
      constraint city_fk1 foreign key(region_id) references Region(id)
  );
  
  CREATE TABLE Feedback(
      -- ...
      id integer primary key not null, 
      -- ...
      firstname varchar(30) not null,
      lastname varchar(30) not null,
      midname varchar(30),
      city_id integer not null,
      phone varchar(127),
      email varchar(255),
      comment text,
      -- ..
      constraint feedback_fk1 foreign key(city_id) references City(id)
  );