Laravelでindexを作成、追加する方法

Schma::create('books', function(Blueprint $table){
	$table->increments('id');
	$table->string('title')->index();
	$table->string('isbn')->unique();
	$table->integer('price');
	$table->integer('author_id');
	$table->timestamps();
});


Schema::table('books', function(Blueprint $table){
	$table->index('title');
});

Schema::table('author_book', function(Blueprint $table){
	$table->index(['author_id', 'book_id']);
});

$table->dropIndex('books_title_index');