Mysql Procedure. Update and Select - mysql

Question

I have a procedure call that updates a set of data and then returns the data set for my to render. Everything works fine except that, I cant do both operations at once. If I do the update, then the procedure, won´t return any value and vice versa. I have seen some answers suggesting to use temptables but I could not find how to retrieve the dataset. I appreciate any help even if it comes to improving my query.
CREATE DEFINER=`root`#`localhost` PROCEDURE `prueba`(IN `idUsuario` INT)
MODIFIES SQL DATA
BEGIN
DECLARE flag INT DEFAULT FALSE;
DECLARE done INT DEFAULT FALSE;
DECLARE idNotificacion INT DEFAULT 0;
DECLARE cont INT DEFAULT 0;
DECLARE resultset CURSOR FOR SELECT id FROM notificaciones WHERE involvedA_idUsuario=idUsuario AND active=1;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN resultset;
SET #query = "SELECT * FROM notificaciones n WHERE n.id IN('null'";
the_loop: LOOP
FETCH resultset INTO idNotificacion;
IF done THEN
LEAVE the_loop;
END IF;
SET cont = cont + 1;
SET flag = TRUE;
SET #query = CONCAT(#query," , " ,idNotificacion);
UPDATE notificaciones SET active=0 WHERE id=idNotificacion;
END LOOP the_loop;
CLOSE resultset;
IF flag THEN
SET #query = CONCAT(#query, ")");
PREPARE stmt FROM #query;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END IF;
END

Answer 1

Do you really need a cursor? An option like this, maybe it can be useful:
/* Procedure structure for procedure `prueba` */
/*!50003 DROP PROCEDURE IF EXISTS `prueba` */;
DELIMITER $$
CREATE PROCEDURE `prueba`(`idusuario` INT)
BEGIN
DECLARE `ids` LONGTEXT DEFAULT NULL;
SELECT GROUP_CONCAT(`id`) INTO `ids`
FROM `notificaciones`
WHERE `involveda_idusuario` = `idusuario` AND `active` = 1;
IF (`ids` IS NOT NULL) THEN
SET #`stmt` := CONCAT('UPDATE `notificaciones`
SET `active` = 0
WHERE `id` IN (', `ids`, ')');
PREPARE `exec` FROM #`stmt`;
EXECUTE `exec`;
SET #`stmt` := CONCAT('SELECT `id`, `involveda_idusuario`, `active`
FROM `notificaciones` `n`
WHERE `n`.`id` IS NULL OR `n`.`id` IN (', `ids`, ')');
PREPARE `exec` FROM #`stmt`;
EXECUTE `exec`;
DEALLOCATE PREPARE `exec`;
END IF;
END$$
DELIMITER ;
You must be careful with GROUP_CONCAT and the system variable group_concat_max_len.
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