Question

我正在尝试执行一个PHP代码，该代码减去存储在名为＆＃39;＆＃39;＆＃39;＆＃39;＆＃39;＆＃39;的mysql表中的数量的-1。该表以10开头，如果使用值caffe执行php，则表中的数量将更新。将是一些良好的代码行，以便我能理解它是如何工作的。

从网址读取值：http://mypage/getdata.php?value=caffe
从数据库表caffe
从表中减去-1
更新mysql表caffe

<?
$servername = "localhost";
$username = "xxx";
$password = "";
$database = "my_ufficina";


//creating a new connection object using mysqli 
$conn = new mysqli($servername, $username, $password, $database);

//if there is some error connecting to the database
//with die we will stop the further execution by displaying a message causing the error 
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}

//if everything is fine

$txt = $_GET['value'];

if ($txt == caffe)
$count = 1;

echo $count;

Answer 1

我会尝试这样的事情：

if ($txt === 'caffe') {

    // get Caffe value :

    try {
        $currentCaffeValue = $conn->query("SELECT yourCaffeValue FROM yourTable");
    } catch (Exception $e) {
        echo 'db read failed : ', $e->getMessage();
    }

    // do your stuff then update Caffe value :

    try {
        $conn->query("UPDATE yourTable SET yourCaffeValue = yourCaffeValue - 1");
    } catch (Exception $e) {
        echo 'db update failed : ', $e->getMessage();
    }
}

顺便说一句，你应该在使用它之前清理$ _GET中的值：http://php.net/manual/en/function.filter-input.php

用PHP从mysql表中减去一个数量

1 个答案: