text: 
  exports.up = function(knex, Promise) {
    return knex.schema.createTable('book', function(table){
      table.increments();
      table.string("title");
      table.string("author").notNullable();
      table.string("genre");
      table.string("image_url");
      table.integer("page_count");
    });
  };
  
  exports.down = function(knex, Promise) {
    return knex.schema.dropTableIfExists('book');
  };
  