How do I catch a query exception in laravel to see if it fails?

The simplest way to catch any sql syntax or query errors is to catch an Illuminate\Database\QueryException after providing closure to your query:

try { 
  $results = \DB::connection("example")
    ->select(\DB::raw("SELECT * FROM unknown_table"))
    ->first(); 
    // Closures include ->first(), ->get(), ->pluck(), etc.
} catch(\Illuminate\Database\QueryException $ex){ 
  dd($ex->getMessage()); 
  // Note any method of class PDOException can be called on $ex.
}

If there are any errors, the program will die(var_dump(...)) whatever it needs to.

Note: For namespacing, you need to first \ if the class is not included as a use statement.

Also for reference:

Laravel 5.5 API – Query Exception

Laravel 8.x API – Query Exception