Notice: undefined variable: id in C:\xampp\xampp\htdocs\BTVN\detail.php on line 19 loi

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I have the problem in line 19. &id

Undefined variable

The error is in the get query but i do not know how to fix it. it have something with the $_id can anyone help me ?

What I have tried:

HTML

  1  <!DOCTYPE html>
  2  <html lang="en">
  3  <head>
  4      <meta charset="UTF-8">
  5      <meta http-equiv="X-UA-Compatible" content="IE=edge">
  6      <meta name="viewport" content="width=device-width, initial-scale=1.0">
  7      <title>Details</title>
  8      <style>
  9          *{margin: 0;padding: 13px;box-sizing:border-box;}
 10          .container{display: flex;}
 11      </style>
 12  </head>
 13  <body>
 14      <?php
 15      require_once( "./config/db.php");
 16      if(isset($_GET['pr_id'])){
 17          $id = $_GET['pr_id'];}
 18      
 19        $sql = "SELECT * FROM product WHERE pr_id= ". $id ;
 20        $result = mysqli_query( $connect, $sql);
 21        if ($result)
 22        {
 23            while ($row = mysqli_fetch_assoc($result))
 24            {?>
 25                <div class="container">
 26                    <div class="pr-left">
 27                        <img src="./image/<?php echo $row['image'] ?>">
 28                    </div>
 29                    <div class="pr-right">
 30                        <h1><?php echo $row['pr_name'] ?></h1>
 31                        <h3>Price: <?php echo $row['price'] ?>VND</h3>
 32                        <button>BUY NOW</button>
 33                        <p>GIAO HÀNG TOÀN QUỐC <br> THANH TOÁN KHI NHẬN HÀNG <br> ĐỔI HÀNG TRONG 15 NGÀY</p>
 34                    </div>
 35                </div>
 36            <?php
 37            }
 38        }
 39        else{echo 'loi';} 
 40      ?>
 41  </body>
 42  </html>

Posted 17-Mar-22 16:27pm

Dieu2002

Updated 17-Mar-22 23:09pm

Richard Deeming

v2

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Comments

Richard Deeming 18-Mar-22 5:09am

Your code is vulnerable to SQL Injection[^]. NEVER use string concatenation/interpolation to build a SQL query. ALWAYS use a parameterized query.
PHP: SQL Injection - Manual[^]
PHP: Prepared statements and stored procedures - Manual[^]

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Richard MacCutchan · Answer 1 · 2022-03-17T23:03:00

Solution 1

You need to learn about the scope of variables.

PHP

if(isset($_GET['pr_id'])){
    $id = $_GET['pr_id']; // $id only exists within the scope of this block
}
// $id no longer exists here
  $sql = "SELECT * FROM product WHERE pr_id= ". $id ;

Posted 17-Mar-22 23:03pm

Richard MacCutchan