通过逐行从数据库中获取数据，使用PHP / MySQL生成QR代码

Question

I am stuck here while generating QR Code using PHP and SQL. Basically I am generating code for students using their ids and other information while fetching data from database. But the problem is that when I click on submit button so that table data store in QR Code, then it only generate the QR Code of of only last one student.

I create submit button on each row so that when I click on submit button then submit the data of that particular row to QR image. But problem is that when I click on submit button of any row then it generate qr image of last student in table. For Example if 1 have 10 students in table, then it generate image of student whose id is 10 and at last row of table.

Code is available here:

<?php
    include('qrlib.php'); 
    function getUsernameFromEmail($student_id) {
        $find = '@';
        $pos = strpos($student_id, $find);
        $username = substr($student_id, 0, $pos);
        return $username;
    }
    if(isset($_POST['submit']) ) {
        $tempDir = 'temp/'; 
        $student_id = $_POST['student_id'];
        $fname =  $_POST['fname'];
        $filename = getUsernameFromEmail($student_id);

        $codeContents = 'mailto:'.$student_id.'?id='.urlencode($student_id).'&fname='.urlencode($fname); 
        QRcode::png($codeContents, $tempDir.''.$filename.'.png', QR_ECLEVEL_L, 5);
    }
?>

Form:

<form id="demo-form2" method="post"  data-parsley-validate class="form-horizontal form-label-left" > 

                                      <table id="datatable" class="table table-striped table-bordered">
                  <thead>
                    <tr>
                      <th>Student Id</th>
                      <th>First Name</th>
                      <th>Actions</th>

                    </tr>
                  </thead>
                      <tbody>
                        <?php
                            include("includes/connection2.php");

                            $sql = "SELECT * FROM student";
                            $result=mysql_query($sql); //rs.open sql,con

                        while ($row=mysql_fetch_array($result))
                        { ?><!--open of while -->
                        <tr>
                            <td><input type="text" value="<?php echo $row['student_id']; ?>" name="student_id" ></td>
                            <td><input type="text" value="<?php echo $row['fname']; ?>" name="fname" ></td>
                        <td class="center">
                                <div class="form-group">
                    <input type="submit" name="submit" class="btn btn-primary submitBtn" style="width:20em; margin:0;" />
                </div>
                            </td>
                            <td class="center">

                            </td>   
                        </tr>
                                                            <?php
                           } //close of while
                        ?>
                      </tbody>
                       <?php
        if(!isset($filename)){
            $filename = "author";
        }
        ?>
        <div class="qr-field">
            <h3>QR Code Result: </h3>
            <center>
                <div class="qrframe" style="border:2px solid black; width:210px; height:210px;">
                    <?php echo '<img src="temp/'. @$filename.'.png" style="width:200px; height:200px;"><br>'; ?>
                </div>
    <a class="btn btn-primary submitBtn" style="width:50px; margin:1px 0;" href="download.php?file=<?php echo $filename; ?>.png ">Download QR Code</a>
            </center>
        </div>
                </table>
                        </div>
                </div>
              </div>
            </div>
</div>
        </div>   
                </form>

Answer 1

You create one submit button for each row, but all of these buttons are inside the same form and therefore they all do the same: submit the entire form, with all of its inputs.

You store the student_id for each student in its own input tag, so you have one for each student, but all inputs have the same name: "student_id".

When the form is submitted (regardless of which specific submit button caused it to be submitted) - the data of all inputs is sent, but since they all have the same name - the last value overwrites all the rest. This is why you always get a result only for the last student.

One way to solve this would be to have separate form for each student, but this will not work with the current table structure.

Another option is to give each submit button a unique name, and then determine which student was submitted in the PHP side, according to the submit button's name.

Another option is to not have a submit button per each student, but just one submit button at the bottom of the form. Then, add a radio button for each student with a unique value (probably the student_id). This way, submitting the form will send the student_id of the selected student to the server.

Probably the "right" way to approach this would be to use JavaScript.