php - 无法使用 PHP 请求从 MySQL 表获取数据

Question

我是 PHP 和 MySQL 的新手，并试图从我的表中返回与 HTML 表单的输入相匹配的行。代码如下:

$connect = mysqli_connect('localhost', 'root', '', 'testdb') 
OR die('Could not connect to the server' . mysqli_connect_error());

$query = ("SELECT * FROM users WHERE username = '$username'");
$result = mysqli_query($connect, $query);
$hits = mysqli_affected_rows($connect);

if ($hits < 1) {
   echo "Incorrect password or username";   
   die("<br /><a href='index.php'>Try Again<a/>");
} else {
   // other not relevant code here
}

当表中存在与查询匹配的数据时，var $hits 始终返回为 0。

var_dump($result) 返回:

object(mysqli_result)#2 (5) { ["current_field"]=> int(0) ["field_count"]=>
int(4) ["lengths"]=> NULL ["num_rows"]=> int(0) ["type"]=> int(0) } 

Answer 1

请发表用户名...并尝试此代码。

 $connect = mysqli_connect('localhost', 'root', '', 'testdb') 
    OR die('Could not connect to the server' . mysqli_connect_error());

    $username=$_POST['username'];

    $query = ("SELECT * FROM users WHERE username = '$username'");

    $result = mysqli_query($connect, $query);
    $hits = mysqli_num_rows($connect);

    if ($hits < 1) {
       echo "Incorrect password or username";   
       die("<br /><a href='index.php'>Try Again<a/>");
    } else {
       // other not relevant code here
    }