PHP初学者.试图显示用户id - PHP beginner. Trying to display UserId

PHP beginner. Trying to display UserId

本文关键字：用户 id 显示初学者 PHP | 更新日期: 2023-09-27

我正在访问PhpMyAdmin上的数据库，我所有的名字等都是正确的，但由于某种原因UserId不工作。有人能给我指个正确的方向吗?

我试过打印，但是没有显示。

<?php session_start(); 
$username = $_GET['username'];
$password = $_GET['password'];

// Create connection

$con=mysqli_connect("localhost","root","","test");
// Check connection
if (mysqli_connect_errno($con))
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$result = mysqli_query($con,"SELECT * FROM user2 where username='$username' and   password='$password'");
$row_cnt = mysqli_num_rows($result);
if($row_cnt >0){
while($row = mysqli_fetch_array($result)){
$UserId = $row['UserId'];
}
$sqlQuery2 = "SELECT ProductID, Name, Price, Description FROM product";
echo "Hello ".$username."<br>" .$UserId.   "<br> This is a list of products";
$result2 = mysqli_query($con,$sqlQuery2);
echo "<table border='1'>
<tr>
<th>ProductID</th>
<th>Name</th>
<th>Price</th>
<th>Description</th>
<th>View</th>
 </tr>";
while($row = mysqli_fetch_array($result2))
 {
 echo "<tr>";
 echo "<td>" . $row['ProductID'] . "</td>";
 echo "<td>" . $row['Name'] . "</td>";
 echo "<td>" . $row['Price'] . "</td>";
 echo "<td>" . $row['Description'] . "</td>";
 echo "<td><a href='"detailview.php?ProductID=".$row['ProductID']."'"'>Detailed View</a></td>";
 echo "</tr>";
 }
echo "</table>";
mysqli_close($con);
?>
<a href="userupdatedetails.php?UserId=<?php echo $UserId ?>">Update My Details</a>
<?php } else{
echo "invalid login "; }
?>

使用var_dump($var)查看变量

中的内容

首先检查$result返回的内容，然后在使用$UserId之前检查它在while检查$UserId是否设置(如果条件为false，您的var没有设置…)之后，您应该检查$row_count也

你应该缩进你的代码
下面是缩进的代码:

<?php session_start(); 
$username = $_GET['username'];
$password = $_GET['password'];

// Create connection

$con=mysqli_connect("localhost","root","","test");
// Check connection
if (mysqli_connect_errno($con))
{
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$result = mysqli_query($con,"SELECT * FROM user2 where username='$username' and   password='$password'");
$row_cnt = mysqli_num_rows($result);
if($row_cnt >0){
    while($row = mysqli_fetch_array($result)){
        $UserId = $row['UserId'];
    }
    $sqlQuery2 = "SELECT ProductID, Name, Price, Description FROM product";
    echo "Hello ".$username."<br>" .$UserId.   "<br> This is a list of products";
    $result2 = mysqli_query($con,$sqlQuery2);
    echo "<table border='1'>
    <tr>
    <th>ProductID</th>
    <th>Name</th>
    <th>Price</th>
    <th>Description</th>
    <th>View</th>
    </tr>";
    while($row = mysqli_fetch_array($result2))
    {
        echo "<tr>";
        echo "<td>" . $row['ProductID'] . "</td>";
        echo "<td>" . $row['Name'] . "</td>";
        echo "<td>" . $row['Price'] . "</td>";
        echo "<td>" . $row['Description'] . "</td>";
        echo "<td><a href='"detailview.php?ProductID=".$row['ProductID']."'"'>Detailed View</a></td>";
        echo "</tr>";
    }
    echo "</table>";
    mysqli_close($con);
    ?>
    <a href="userupdatedetails.php?UserId=<?php echo $UserId ?>">Update My Details</a>
    <?php
}
else
{
    echo "invalid login ";
}
?>