Laravel查询生成器：未找到类

I keep receiving an error when running this code

public function postTypeAhead($query)
{    

     $q = $this->prepareQuery($query);

     $results = DB::table('postcode_db')
                         ->select('postcode', 'suburb', 'state', 'lon', 'lat')
                         ->where('suburb', 'LIKE', $q) 
                         ->get();

    return Response::json($results);
}

{"error":{"type":"Symfony\\Component\\Debug\\Exception\\FatalErrorException","message":"Class 'Lib\\Services\\Search\\DB' not found","file":"\/home\/tes123\/public_html\/app\/lib\/Services\/Search\/Autocomplete.php","line":162}}

I'm trying to match a string with suburb from the postcode_db table

It seems you are using namespaces because autoloader could not find DB class in current scope. Try to write use DB; at the beginning of your file OR use fully qualified class name (since there is alias DB in root namespace you can just use backslash prefix):

public function postTypeAhead($query)
{    
     $q = $this->prepareQuery($query);

     $results = \DB::table('postcode_db')
                     ->select('postcode', 'suburb', 'state', 'lon', 'lat')
                     ->where('suburb', 'LIKE', $q) 
                     ->get();

    return Response::json($results);
}