如何使用PHP从MySQL检索特定值? [英] How do I retrieve a specific value from MySQL with PHP?

问题描述

好吧，我真受够了.在过去的一周中，我将大部分空闲时间都花在了此事上.我知道查询在SQL中已更改，但我无法弄清楚.我可以找到的所有其他帖子似乎已经过时了.如果有人可以帮助我，我将非常感激.

Okay I'm so fed up. I've spent the better part of my free time for the past week trying to figure this out. I know that the query has changed in SQL but I cant figure it out. All of the other posts I can find seem to be outdated. If anyone could help me out I would really appreciate it.

我要做的就是通过使用唯一输入到数据库的唯一密码"来检索行的ID，然后将其设置为会话数据，以便可以在其他页面上使用该数据.我觉得这应该不难.

All I am trying to do is retrieve the id of a row by using a unique "passphrase" that I manually entered into a database and then set that as session data so that I can use that data on other pages. I feel like it shouldn't be this hard.

出于演示目的，这是我使用较旧的mysql_query的代码.

For demostration purposes here is my code using the older mysql_query.

<?php
$dbhost = 'localhost';
$dbuser = 'root';
$dbpass = 'test321';

$db = 'local_test';

$conn = mysql_connect($dbhost,$dbuser,$dbpass);
mysql_select_db($db);  ?>



<?php

include 'includes/connection.php';

$pass = $_POST['inputPass'];

if(!$_POST['submit']) {
    echo "please fill out the form";
    header ('location: user_authenticate.php');
}


$query = "SELECT id FROM users WHERE pass= '$pass'";

$id = mysql_query($query);


$_SESSION["userId"] = "$id";

print $pass;
print $id;
print $_SESSION["userId"];?>

我尝试了很多事情，所以遇到很多不同的错误.我希望有人可以在这里指出正确的方向.最好的方法是什么?

I've tried a lot of things so I've gotten a lot of different errors. I am hoping someone could point me in the right direction here. What is the best way to do this?

推荐答案

首先，请不要使用mysql API；已弃用，在PHP 7中不起作用.

First off, don't use the mysql API; it's deprecated and won't work in PHP 7.

现在，这已经不合时宜了，mysql_query()返回一个结果集资源(就像一个对象)，其中可以包含多行，其中可以包含 >多列.要访问此资源的内容，必须将fetch行插入数组，然后为所需列的索引进入该数组.您需要执行以下操作:

Now that that's out of the way, mysql_query() returns a result set resource (which is like an object) which can contain multiple rows which can contain multiple columns. To access the contents of this resource, you have to fetch a row into an array and then index into that array for the column you want. You need to do something like this:

$query = "SELECT id FROM users WHERE pass= '$pass'";
$result = mysql_query($query);
$row = mysql_fetch_assoc($result);
$id = $row['id'];

，然后您可以使用$id的值.

and then you can use the value of $id.

mysqli::query()同样适用，它返回一个mysqli_result对象.

The same holds for mysqli::query(), which returns a mysqli_result object.

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