have you debug / print the query built from your Query Builder ? and paste it here

Try:

DB::table('groups')
    ->where('code', '=', $code)
    ->set('members', DB::raw('concat(members, '.$userId.')'))
    ->update();

I recommend always using the 3 argument version of the where() method variants and placing each method on a new line for readability, indenting only once where appropriate.

Hi Shawn, thanks for the help! One more issue. I am now using:

DB::table('groups')
->where('code', '=', Input::get('code'))
->set('members', DB::raw('concat(members, '.Auth::user()->id.')'))
->update();

and get "Call to undefined method Illuminate\Database\Query\Builder::set()"

if (starts_with($method, 'where'))
	{
		return $this->dynamicWhere($method, $parameters);
	}

	$className = get_class($this);

	throw new \BadMethodCallException("Call to undefined method {$className}::{$method}()");
}

Is there a way to include this method (I dont seem to see a set method, perhaps I'm looking in the wrong place) or another method all together?

i have similar problem, any help and solution would be nice :)

look at http://laravel.com/docs/queries#updates

ps why do you need concat? you have to power of PHP

solution for this problem: http://stackoverflow.com/questions/22098600/laravel-4-concat-issues