            $cities[$key] = implode(', ', $value);
        }

        // Only keep one city (the first and also most important) for each set of possibilities.
        $cities = array_unique($cities);

        // Sort by area/city name.
        ksort($cities);

        return $cities;
    }
The software constructs all or part of an SQL command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended SQL command when it is sent to a downstream component.