public function getSql(SqlWalker $sqlWalker)
    {
        $entityLocation = $this->entityLocation->dispatch($sqlWalker);
        return sprintf('earth_distance(ll_to_earth(%s[0], %s[1]),ll_to_earth(%s, %s))',
            $entityLocation,
            $entityLocation,
            $this->latitude->dispatch($sqlWalker),
            $this->longitude->dispatch($sqlWalker)
        );
    }