title: Oracle SQL Trigger insert new records based on a insert column value
body: <p>I'm trying to create a trigger for a Oracle table. Here are the requirements
  I have two tables Books, Copies (Books &amp; copies have a 1 to n relationship. Each book can have 0 to n copies)</p>
  
  <p>Book Table:</p>
  
  <pre><code>CREATE TABLE Book
    (
      book_id      INTEGER NOT NULL ,
      isbn         VARCHAR2 (20) NOT NULL,
      publisher_id INTEGER NOT NULL ,
      tittle       VARCHAR2 (100) NOT NULL ,
      cat_id       INTEGER NOT NULL ,
      no_of_copies INTEGER NOT NULL ,
      ....
      CONSTRAINT isbn_unique UNIQUE (isbn),
      CONSTRAINT shelf_letter_unique UNIQUE (shelf_letter, call_number) 
    ) ;
  </code></pre>
  
  <p>Copies Table</p>
  
  <pre><code>CREATE TABLE Copies
    (
      copy_id     INTEGER NOT NULL ,
      book_id     INTEGER NOT NULL ,
      copy_number INTEGER NOT NULL,
      constraint copy_number_unique unique(book_id,copy_number)
    ) ;
  </code></pre>
  
  <p>The trigger (on update,edit of a the Book table) should add its corresponding copy records into Copies table. So if a insert into Books table has  Book.no_of_copies as 5 then five new records should be inserted into the Copies table..</p>