title: How to display data from the object
body: <p>When I use SELECT to display the table, in the column the ID and Subject column is displayed with content, but in the date column only SYSTEM.DATAS is displayed</p>
  
  <pre><code>create or replace type dataS as object
  (
      city VARCHAR2(20),
      year NUMBER,
      publishing VARCHAR2(40),
      constructor function dataS (city number, year number,
      publishing varchar2) return self as result,
      member procedure print  
  );
  
  </code></pre>
  
  <pre><code>create or replace type body dataS
  is
      constructor function dataS (city number, year number,
      publishing varchar2) return self as result
          is
          begin
          self.city := city;
          self.year := year;
          self.publishing := publishing;
          return;
      end;
      member procedure print
      is
      begin
          dbms_output.put_line( self.city || ',' || self.year || ',' || self.publishing);
      end;
  end;
  </code></pre>
  
  <pre><code>create or replace type book as object
  (
      idBook number,
      subject VARCHAR2(20),
      data dataS,
      constructor function book (idBook number, subject varchar2, data dataS) return self as result,
      member procedure print
  );
  </code></pre>
  
  <pre><code>create or replace type body book
  is
      constructor function book (idBook number, subject varchar2, data dataS)
    return self as result
          is
          begin
          self.idBook := idBook;
          self.subject := subject;
          self.data := data;
  
          return;
      end;
      member procedure print
      is 
      begin
          dbms_output.put_line(self.idBook || ',' || self.subject);
          self.datadane.print();
      end;
  end;
  </code></pre>
  
  <pre><code>create table books of book
  (
      idBooks not null,
      subject not null,
  
      constraint ck_publishing check (data.wpublishing is not null),
      constraint pk_books primary key (idBooks),
      constraint u_year unique(data.year)
  );
  </code></pre>
  
  <pre><code>INSERT INTO books VALUES (1, 'Thiller', 
  (dataS('Tokyo', 1994,'XXX')));
  </code></pre>
  
  <p>How I can display the year, publishing and city in the date column?</p>