PHP에서 입력 및 출력 매개변수를 모두 사용하여 MySQL 저장 프로시저를 호출하는 방법은 무엇입니까?

DELIMITER $$
CREATE PROCEDURE `test_proc`(
    IN input_param_1 INT,
    IN input_param_2 INT,
    IN input_param_3 INT,
    OUT output_sum INT,
    OUT output_product INT,
    OUT output_average INT
)
BEGIN
    SET output_sum = input_param_1 + input_param_2 + input_param_3;
    SET output_product = input_param_1 * input_param_2 * input_param_3;
    SET output_average = (input_param_1 + input_param_2 + input_param_3) / 3;
END$$
DELIMITER ;

mysqli_stmt_bind_param($call, 'iii', $procInput1, $procInput2, $procInput3);

$select = mysqli_query($mysqli, 'SELECT @sum, @product, @average');
$result = mysqli_fetch_assoc($select);

$procInput1 = 123;
$procInput2 = 456;
$procInput3 = 789;

$mysqli = mysqli_connect();

$call = mysqli_prepare($mysqli, 'CALL test_proc(?, ?, ?, @sum, @product, @average)');
mysqli_stmt_bind_param($call, 'iii', $procInput1, $procInput2, $procInput3);
mysqli_stmt_execute($call);

$select = mysqli_query($mysqli, 'SELECT @sum, @product, @average');
$result = mysqli_fetch_assoc($select);

$procOutput_sum     = $result['@sum'];
$procOutput_product = $result['@product'];
$procOutput_average = $result['@average'];