"；未定义变量“；在尝试读取行时 - "Undefined Variable" while trying to read rows

"Undefined Variable" while trying to read rows

本文关键字：读取 quot 未定义变量 | 更新日期: 2024-04-06

我试图读取一堆行并在没有通常的"ARRAY=>"垃圾的情况下显示它们，但我得到的只是这个错误

注意：未定义的变量：第0行上C:''examplep''htdocs''sql.php中的数据

这是我的代码：

<?php virtual('/Connections/TDBS_local.php');
$query = "SELECT sub_category FROM sub_category WHERE main_category_id = 2 ";
$result = mysqli_query($TDBS_local, $query);
if ($result = mysqli_query($TDBS_local, $query)) {
/* fetch associative array */
if($row = mysqli_fetch_assoc($result)) {
    $data = unserialize($row['sub_category']);
}
/* free result set */
mysqli_free_result($result);
}
 print "<pre>";
 print_r($data);
 print "</pre>";
?>

我哪里错了？

以下是如何使用pdo、mysqli和mysql

MYSQLI

    $con=mysqli_connect("localhost","username","password","dbname");
    $sql="SELECT sub_category FROM sub_category WHERE main_category_id = 2";
    $result=mysqli_query($con,$sql);
    $new_array = array();
    while ($row = mysqli_fetch_array($result,MYSQLI_ASSOC)){
        $new_array[] = $row;
    }
    print_r($new_array);
    mysqli_free_result($result);
    mysqli_close($con);

MYSQL-

mysql_connect("localhost","username","password");
mysql_select_db("dbname"); 
$result = mysql_query("SELECT sub_category FROM sub_category WHERE main_category_id = 2");
$new_array = array();
while ($row = mysql_fetch_array($result)) {
    $new_array[] = $row;
}
print_r($new_array);

PDO-

$pdo = new PDO('mysql:host=localhost;dbname=dbname', 'username', 'password');
$statement = $pdo->query("SELECT sub_category FROM sub_category WHERE main_category_id = 2");
$new_array = array();
while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
    $new_array[] = $row;
}
print_r($new_array);

我认为您必须使用require或include而不是virtual:

<?php
require('Connections/TDBS_local.php');
$data = '';
$query = "SELECT sub_category FROM sub_category WHERE main_category_id = 2 ";
$result = mysqli_query($TDBS_local, $query);
if ($result = mysqli_query($TDBS_local, $query)) {
/* fetch associative array */
if($row = mysqli_fetch_assoc($result)) {
    $data = unserialize($row['sub_category']);
}
/* free result set */
mysqli_free_result($result);
}
 print "<pre>";
 print_r($data);
 print "</pre>";
?>