私はMySQLにこの手順を持っています（カーソルが開かれている部分を見てください）
/* PROCEDURE 1 : Post notification */
DROP PROCEDURE IF EXISTS AddNotificationOnPosts;
DELIMITER $$
CREATE DEFINER=`root`@`localhost` PROCEDURE `AddNotificationOnPosts`(arg_from_user INT(11),arg_on_post_id INT(11),arg_in_group_id INT(11))
BEGIN
DECLARE num_rows INT DEFAULT NULL;
DECLARE insert_result INT DEFAULT NULL;
DECLARE done INT DEFAULT 0;
DECLARE var_user_id INT DEFAULT NULL;
DECLARE c1 CURSOR FOR
SELECT user_id
FROM user_rights
WHERE user_rights.right = 101 AND user_rights.group_id = arg_in_group_id
ORDER BY user_id DESC;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
IF(arg_from_user IS NULL OR arg_from_user = '')
THEN
SELECT "0" AS response;
ELSEIF(arg_on_post_id IS NULL OR arg_on_post_id = '')
THEN
SELECT "0" AS response;
ELSEIF(arg_in_group_id IS NULL OR arg_in_group_id = '')
THEN
SELECT "0" AS response;
ELSE
SELECT count(notification_id) FROM notifications_posts
WHERE
from_user = arg_from_user AND
on_post_id = arg_on_post_id AND
in_group_id = arg_in_group_id
INTO num_rows;
END IF;
IF num_rows = 0
THEN
INSERT INTO notifications_posts(from_user,on_post_id,in_group_id) VALUES(arg_from_user,arg_on_post_id,arg_in_group_id);
SELECT ROW_COUNT() INTO insert_result;
IF insert_result > 0
THEN
/* Increment the notifications for every user*/
OPEN c1;
read_loop: LOOP
FETCH c1 INTO var_user_id;
IF done THEN
LEAVE read_loop;
ELSE
IF NOT(var_user_id = arg_from_user)
THEN
/* UPDATING */
UPDATE user_info SET notifications = notifications + 1 WHERE user_info.user_id = var_user_id;
/* SELECTING RESULT */
SELECT
user_info.user_id,
messages,
tasks,
notifications,
messages+tasks+notifications AS total
FROM user_rights
INNER
JOIN user_info
ON user_info.user_id = user_rights.user_id
WHERE user_rights.right = 101 AND user_rights.group_id = arg_in_group_id ;
END IF;
END IF;
END LOOP;
CLOSE c1;
ELSE
SELECT "0" AS response;
END IF;
ELSE
SELECT "0" AS response;
END IF;
END $$
DELIMITER ;
そしてこの部分で
/* Increment the notifications for every user*/
OPEN c1;
read_loop: LOOP
FETCH c1 INTO var_user_id;
IF done THEN
LEAVE read_loop;
ELSE
IF NOT(var_user_id = arg_from_user)
THEN
/* UPDATING */
UPDATE user_info SET notifications = notifications + 1 WHERE user_info.user_id = var_user_id;
/* SELECTING RESULT */
SELECT
user_info.user_id,
messages,
tasks,
notifications,
messages+tasks+notifications AS total
FROM user_rights
INNER
JOIN user_info
ON user_info.user_id = user_rights.user_id
WHERE user_rights.right = 101 AND user_rights.group_id = arg_in_group_id ;
END IF;
END IF;
END LOOP;
CLOSE c1;
手順はデータを選択してから更新します（信じてください、私は真剣です）。XML変更されたデータで生成しているので、後で選択する必要があります。
1 select が update の下にあることがわかっているので、select を選択してから update を行うのはなぜですか?
2 このような「素晴らしいアイデア」を持っていたのは誰ですか?
ありがとうございました。