PDO 值递增 PHP、Mysql [英] PDO Value Increment PHP, Mysql

问题描述

大家好，我正在研究一个处理事件点的项目.我正在尝试在有人注册后更新事件点的值.有人注册或从数据库读取值没有问题，但我无法更新这些点.希望能帮到你..

Hello guys im working on a project for handling spots on a event. I'm trying to update the values of the event spots after someone registers to it. There is no problem with someone registering or reading the values from database but i cant update the spots. Hope you can help..

这是代码的不工作部分:

Here is the not working part of the code :

$free_spots_new = $free_spots - 1 ; // i haven't written the code up there, $free_spots is the value of the free_spots value in the database. And this is the process after someone registers to this event ...
$full_spots_new = $full_spots + 1 ; // same in here

try{
$update_event_query = "UPDATE `events` SET `free_spots` = :free_spots, `full_spots`= :full_spots WHERE `event_id`=:event_id";
$update_event_query_do = $db->prepare($update_event_query);
$update_event_query_do -> bindParam(':free_spots', $free_spots_new, PDO::PARAM_INT);
$update_event_query_do -> bindParam(':full_spots', $full_spots_new, PDO::PARAM_INT);
$update_event_query_do ->execute() or die(print_r($update_event_query_do->errorInfo(), true));
}

catch(PDOException $e) {
$log->logError($e." - ".basename(__FILE__));
}

还可以在不定义新变量(如 $free_spots_new exc)的情况下更新 UPDATE 行中的值.

Also is it possible to update the values within the UPDATE line without defining a new variable like $free_spots_new exc.

推荐答案

Beside the missing '

Beside the missing '

您可以直接在查询中执行更改:

You can execute the alterations directly in the query:

UPDATE `events`
SET    `free_spots` = `free_spots`-1,
       `full_spots` = `full_spots`+1
WHERE  `event_id`   = :event_id

您还需要绑定 :event_id 占位符$update_event_query_do->bindParam(':event_id', $event_id, PDO::PARAM_INT);

Your also need to bind the :event_id placeholder $update_event_query_do->bindParam(':event_id', $event_id, PDO::PARAM_INT);

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