PHP表单提交仅刷新无输出问题求助（附代码与表结构）

Hey there, let's walk through fixing your issue—there are a few straightforward mistakes in your code that are causing the page to refresh without showing your $str content. Let's break them down and fix each one:

1. Form Method Typo (Critical!) #

Look at your form code:

<form action="case_status.php" action="POST">

You've got two action attributes here—this is invalid HTML. The second one should be method="POST" instead. Forms default to GET requests, so your $_POST checks were never triggering, which is why the page just refreshes. Fix it to:

<form action="case_status.php" method="POST">

2. Submit Button Name Mismatch #

In your PHP, you're checking for:

if(isset($_POST['submit button'])){

But your submit button's name attribute is submit_button (with an underscore, not a space). This condition will never be true, so none of your form processing code runs. Correct it to:

if(isset($_POST['submit_button'])){

3. Undefined Variable in Your Output String #

In your $str HTML, you reference $next_hearing, but earlier in your code you assigned that value to $date:

$date=$row['next_hearing'];

Either rename the variable to $next_hearing when fetching the row, or use $date in your output—otherwise, that field will be empty or throw an undefined variable notice.

4. Add SQL Error Handling (For Debugging) #

You mentioned you're unfamiliar with SQL error handling, but this is key to diagnosing why queries might fail. After running your query, add a check to catch and display errors:

$query=mysqli_query($con,"SELECT * FROM case_details WHERE cs_number='$case_no'");
if (!$query) {
    die("SQL Query Failed: " . mysqli_error($con));
}

This will tell you immediately if there's a problem with your query (like a typo in a column name or table name).

5. Fix SQL Injection Vulnerability #

Directly inserting user input into your SQL query is a huge security risk—attackers can exploit this to manipulate your database. Use prepared statements instead, which are safer:

// Prepare the query with a placeholder
$stmt = mysqli_prepare($con, "SELECT * FROM case_details WHERE cs_number = ?");
// Bind the integer parameter (since cs_number is an int)
mysqli_stmt_bind_param($stmt, "i", $case_no);
// Execute the statement
mysqli_stmt_execute($stmt);
// Get the result set
$result = mysqli_stmt_get_result($stmt);
// Fetch the row
$row = mysqli_fetch_array($result);

6. Start the Session #

You're using $_SESSION['cs_no'] but haven't started the session at the top of your script. Add session_start() before including your config file, otherwise session variables won't work:

<?php
session_start();
require 'config/config.php';
// Rest of your code...

Bonus: Improve Output Placement #

Right now you only echo $str inside the form submission condition. If you move the echo $str; outside the condition (above or below the form), you'll see the results (or error messages) consistently after submission, which is better for user experience.

Corrected Full Example (Key Sections) #

<?php
session_start();
require 'config/config.php'; 
$case_no = ""; 
$str = ""; // Initialize to avoid undefined variable notices

if(isset($_POST['submit_button'])){ 
    $case_no = strip_tags($_POST['cs_no']); 
    $_SESSION['cs_no'] = $case_no; 

    // Use prepared statement for safety
    $stmt = mysqli_prepare($con, "SELECT * FROM case_details WHERE cs_number = ?");
    mysqli_stmt_bind_param($stmt, "i", $case_no);
    mysqli_stmt_execute($stmt);
    $result = mysqli_stmt_get_result($stmt);

    if (!$result) {
        $str = "<p>Error: " . mysqli_error($con) . "</p>";
    } elseif(mysqli_num_rows($result) === 0) {
        $str = "<p>No case found with that number.</p>";
    } else {
        $row = mysqli_fetch_array($result); 
        $filed_by = $row['filed_by']; 
        $defender = $row['defender']; 
        $district = $row['district']; 
        $status = $row['status']; 
        $details = $row['details']; 
        $next_hearing = $row['next_hearing']; 
        $updates = $row['updates']; 

        $str = "<div class='case_body'> 
                <table> 
                    <tr> <td>case no: $case_no</td> </tr> 
                    <tr> <td>filed by: $filed_by</td> </tr> 
                    <tr> <td>defender: $defender</td> </tr> 
                    <tr> <td>district: $district</td> </tr> 
                    <tr> <td>status: $status</td> </tr> 
                    <tr> <td>case details: $details</td> </tr> 
                    <tr> <td>next hearing: $next_hearing</td> </tr> 
                    <tr> <td>updates: $updates</td> </tr> 
                </table> 
            </div>"; 
    }
} 
?> 
<!DOCTYPE html> 
<html> 
<head> <title>Case Status Lookup</title> </head> 
<body> 
    <h3>Enter your case number below to view details</h3> 
    <?php echo $str; ?>
    <form action="case_status.php" method="POST"> 
        <input type="text" name="cs_no" placeholder="Enter case number" required> 
        <input type="submit" name="submit_button" value="Check Status"> 
    </form> 
</body>
</html>

内容的提问来源于stack exchange，提问作者Swagath Shetty