[英]Undefined index error on php
i am getting "Notice: Undefined index: brand in C:\\folder\\folder\\folder\\folder\\file.php on line 8" can some one tell me why is this ?我收到“注意:未定义索引:品牌在 C:\\folder\\folder\\folder\\folder\\file.php 中”,有人能告诉我这是为什么吗? here's my code below you can see line 8 below
这是我的代码,您可以在下面看到第 8 行
<?php
require_once '../core/init.php';
$id = $_POST['id'];
$id = (int)$id;
$sql = "SELECT * FROM products WHERE id = '$id'";
$result = $db->query($sql);
$product = mysqli_fetch_assoc($result);
$brand_id = $product['brand'];
$sql = "SELECT brand FROM brand WHERE id = '$brand_id'";
$brand_query = $db->query($sql);
$brand = mysqli_fetch_assoc($brand_query);
?>
Let me explain the error in detail with an example.让我用一个例子详细解释这个错误。
'Undefined index' error occurred because the associative array returned by
mysqli_fetch_assoc()
does not contain an index named 'brand'.发生“未定义索引”错误是因为
mysqli_fetch_assoc()
返回的关联数组不包含名为“brand”的索引。
So you can use var_dump()
to take a peek and see the actual contents of $product variable like this, example:因此,您可以使用
var_dump()
来查看一下 $product 变量的实际内容,例如:
<?php
$product = ['name'=>'Item1', 'price'=>10];
$anothervariable = $product['brand'];//which gives the error
//doing a var dump to see the contents of $product
var_dump($product);
?>
Output:输出:
Notice: Undefined index: brand in /var/www/html/test/register.php on line 3 array(2) { ["name"]=> string(5) "Item1" ["price"]=> int(10) }
注意:未定义索引:brand in /var/www/html/test/register.php on line 3 array(2) { ["name"]=> string(5) "Item1" ["price"]=> int( 10) }
which obviously doesn't contain ["brand"].
显然不包含 ["brand"]。
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