Laravel : Codition To Insert Tarificationtache (Syntax Error Or Access Violation)

I have to insert to 'technicien'='technician' there 'tache'='task' and 'tarification' ='price'

Schema::create('tarificationtaches', function (Blueprint $table) {
        $table->increments('id');
        $table->float('tarif', 8,2);
        $table->integer('tache_id')->unsigned();
        $table->foreign('tache_id')->references('id')->on('taches');
        $table->integer('technicien_id')->unsigned();
        $table->foreign('technicien_id')->references('id')- 
        >on('techniciens');
        $table->datetime('deleted_at')->nullable();
        $table->timestamps();
    });

each techncien have to make there 'tache' then I would like to add a condition in my function to check the insertion if the 'tache' already exists if yes it displays to me existing' tache' if it does not insert in the database

 public function store(Request $request)
    {

    $tarification = new tarificationtache();
    $tarification ->tache_id = $request->input('tache_id');
    $tarification ->Tarif =$request->input('Tarif');
    $tarification->technicien_id = $request->input('technicien_id');
    $tarification->save();

    return redirect('technicien');  
   }

I have tried this function but i have some error

 public function store(Request $request)
  {

    $tarification = new tarificationtache();
    $tarification ->tache_id = $request->input('tache_id');
    $tarification ->Tarif =$request->input('Tarif');
    $tarification->technicien_id = $request->input('technicien_id');
    $tarification = DB::select("select * FROM tarificationtaches where 
     technicien_id = 'technicien_id' and tache_id = input('tache_id')");
        if(request($tarification) > 1)
         echo "Ce technicien a cette tarification";
        else{

        $tarification->save();

 }}

errors

SQLSTATE[42000]: Syntax error or access violation: 1305 FUNCTION 
 projet2.input 
    does not exist (SQL: select * FROM tarificationtaches where \n
     technicien_id = 'technicien_id' and tache_id = input('tache_id'))

form to inset tache and tarif

Based on what I can understand, maybe you need something like this?

public function store(Request $request)
{
    $count = tarificationtache::where('technicien_id', $request->input('technicien_id'))
        ->where('tache_id', $request->input('tache_id'))
        ->count();
    if ($count > 0) {
        // TODO: adjust response according to your need
        return response()->json(['error' => "Ce technicien a cette tarification"], 400);
    } else {
        $tarification = new tarificationtache;    
        $tarification->tache_id = $request->input('tache_id');
        $tarification->Tarif = $request->input('Tarif');
        $tarification>technicien_id = $request->input('technicien_id');
        $tarification->save();
        // TODO: adjust response according to your need
        return response()->json($tarification);
    }
}

You can check the doc for further details regarding count or any other query builder methods in Laravel.