Select value from view to controller

I'm trying to pass a selected value in a dropdown from my view to my controller so i can make a query later.

Here is my view with the select object:

 <Select class="selectsector" id="ColumnType" name="ColumnType">
    <option value=""> Select something </option>
    <option value="">  option 1 </option>
    <option value="">  option 2 </option>
 </select>

Then according to documentation and a lot of answer/examples i'm trying to get the value from the select on this line:

My route:

 Route::get('kitysoftware/ColumnType/{ColumnType}', [
 "uses" => 'SubSectorsBPIsDataController@TrendFilter',
 "as" => 'trend'
  ]);

My controller:

  public function TrendFilter($ColumnType)
  {
  $SelectedTrend = DB::table('SubSectorsBPIsData')->select('SectorID', 'ColumnType')->where('ColumnType', $ColumnType)->get();
    echo $selectedTrend; //or whatever else i want to do        
}

Error I keep getting: Undefined variable: ColumnType (View: ... I have tried to change several variables names in that line: *Where does it comes from that undefined variable: $ColumnType ? I'm not reloading the page since i want to collect several dropdowns values and then make the query. Not sure if i got the right approach, maybe there is a better way to make it work. JavaScript maybe?
Thanks in advance.

via Chebli Mohamed