显示MySQL数据 <select>失败

Question

I am simply trying to display an html <select> drop down that displays options from MySQL database rows. As far as I can tell this should be working. However, it is not displaying anything in the drop down. the campaigns table definitely has data in the campaignid and name columns. Not sure why it isn't display anything. Please help.

the form that should display name

<?php
//include db connect
  include ("db_con.php");



   //campaign change form function
  function changeCampaign() {
    //set variables
    $query = mysqli_query($con,"SELECT * FROM campaigns");
    //echo form
    echo '<table border="1">
          <form action="functions/campaign_change.php" name="campaignChange" method="post">
            <tr>
              <td><select name="campaignList">';
                    //loop campaigns
                    while ($row = mysqli_fetch_array($query)) {
                      echo "<option value='" . $row['campaignid'] . "'>" . $row['name'] . "</option>";
                    }
        echo '</select></td>
            </tr>
            <tr>
              <td><input type="submit" value="Load" /></td>
            </tr>
          </form>
        </table>';
}
?>

And then I am simply calling the changeCampaign(); function, which IS displaying the form with <select> just no content in it.

The following code was added to show a successful script adding to the same table

here is the form to create a campaign

//campaign creation form function
  function createCampaign() {
    echo '<table border="1">
          <form action="functions/campaign_create.php" name="campaignCreate" method="post">
            <tr>
              <td><input type="text" name="name" placeholder="Enter Campaign Name" required /></td>
            </tr>
            <tr>
              <td><center><input type="submit" name="Create" /></center></td>
            </tr>
          </form>
          </table>';
}

campaign_create.php

<?php
//include db connect
  include ("db_con.php");

//start session
  session_start();

//set variable names
  $username = $_SESSION['username'];
  $campaignname = addslashes($_POST['name']);

//validate campaign name length
  if ((strlen($campaignname) < 6) || (strlen($campaignname) > 55)) {
    echo 'Campaign name must be between 6 and 55 characters - Please go back and try again.';
    exit;
  }

//create new campaign
  $query = mysqli_query($con, "INSERT INTO campaigns (creator, name) VALUES ('".$username."', '".$campaignname."')");
  if ($query) {
    echo 'Campaign created successfully!';
    header( "refresh:2;url=../index.php" );
  } else {
    echo 'There was an unknown error in creating the campaign - Please go back and try again.';
  }

?>

PS - Yes, campaignid is a row in the table, and does have data in it.

Answer 1

You need to echo a close select tag. Just add this line after your loop and you'll be fine

echo '</select>';

Also try changing the first line of your loop to this:

while ($row = mysqli_fetch_array($con, $query)) {

Answer 2

First, your <select> HTML tag is never closed with a </select> .

Second, the $con variable is not usable from within the changeCampaign function scope. Add global $con; to the beginning of the function to fix it.

Additionally, I prefer to jump in and out of PHP blocks with this kind of stuff. Consider this code:

<?php
//include db connect
include ("db_con.php");

//campaign change form function
    function changeCampaign() {
    global $con; // we need the connection data in here.
    //set variables
    $query = mysqli_query($con,"SELECT * FROM campaigns");
?>
<table border="1">
    <form action="functions/campaign_change.php" name="campaignChange" method="post">
        <tr>
            <td><select name="campaignList">';
<?php
                    //loop that is NOT displaying the name
                    while ($row = mysqli_fetch_array($query)) {
                        echo "<option value='" . $row['campaignid'] . "'>" . $row['name'] . "</option>";
                    }
?>
            </select></td>
        </tr>
        <tr>
            <td><input type="submit" value="Load" /></td>
        </tr>
        </form>
    </table>';
<?php
}
?>

In this, you have HTML code that is outputted just as if it had been echo ed, but it is much nicer.