AuthorBooks\Model\AuthorBookSchema::schema PHP Method

    public function schema()
    {
        $this->column('author_id')->refer('Author')->required();
        $this->column('book_id')->refer('Book')->required();
        $this->column('created_on')->isa('str')->timestamp();
        $this->belongsTo('book', 'Book')->by('book_id')->onDelete('CASCADE')->onUpdate('CASCADE');
        $this->belongsTo('author', 'Author')->by('author_id')->onDelete('CASCADE')->onUpdate('CASCADE');
    }