Update data in laravel 6 - laravel

Question

I try to create crud in laravel 6. Create, Read and Delete process is running well. But when Update process, the data in table not change. Could anyone help me to find the problem ? The following my code.
Route
Route::get('/blog', 'BlogController#index');
Route::get('/blog/add','BlogController#add');
Route::post('/blog/store','BlogController#store');
Route::get('/blog/edit/{id}','BlogController#edit');
Route::post('/blog/update','BlogController#update');
Controller
public function index()
{
$blog = DB::table('blog')->get();
return view('blog',['blog' => $blog]);
}
public function edit($id)
{
$blog = DB::table('blog')->where('blog_id', $id)->get();
return view('edit', ['blog'=>$blog]);
}
public function update(Request $request)
{
DB::table('blog')->where('blog_id',$request->blog_id)->update([
'blog_title' => $request->title,
'author' => $request->author]);
return redirect('/blog');
}
View
#foreach ($blog as $n)
<form method="post" action="/blog/update" />
{{ csrf_field() }}
Title <input type="text" name="title" value="{{ $n->title}}">
Author<input type="text" name="author" value="{{ $n->author}}">
<button type="submit" class="btn btn-secondary">Update</button>
</form>
#endforeach

Answer 1

You must provide id in your route
Route::post('/blog/update/{id}','BlogController#update');
In update method add parameter id and then find product against id
public function update(Request $request, $id)
{
DB::table('blog')->where('blog_id',$id)->update([
'blog_title' => $request->title,
'author' => $request->author]);
return redirect('/blog');
}
#foreach ($blog as $n)
<form method="post" action="{{ route('your route name'), ['id' => $$n->id] }}" />
{{ csrf_field() }}
Title <input type="text" name="title" value="{{ $n->title}}">
Author<input type="text" name="author" value="{{ $n->author}}">
<button type="submit" class="btn btn-secondary">Update</button>
</form>
#endforeach

Answer 2

try separating the update into two statements like so
$blog = DB::table('blog')->where('blog_id',$id)->first();
$blog->update([
'blog_title' => $request->title,
'author' => $request->author]);
Also you might want to use models in the future so you can do it like
$blog = Blog::where('blog_id',$id)->first();
Doesn't really shorten your code but it improves the readibility.

Answer 3

Do your update like this:
public function update(Request $request)
{
$post = DB::table('blog')->where('blog_id',$request->blog_id)->first();
$post->blog_title = $request->title;
$post->author = $request->author;
$post->update();
return redirect('/blog');
}