使用表条目加一个填充文本框？

I am trying to increment project number based on the last entry. The the primary key PROJECTNOID auto-increments but is not the same format as the project number (Ex: PROJECTNOID = 1 and Project Number = 19000). I don't want this to be a dropdown box even though some of my code shows the opposite.

<?php
   connect = mysqli_connect("**", "**", "**", "**");

   $query4 = "SELECT PROJECTNOID, ProjectNumber FROM tblProjects ORDER BY 
              PROJECTNOID";
   $result4 = mysqli_query($connect,$query4);

   $options4 = "";

   while($row4 = mysqli_fetch_row($result4);){
      $options4 = $options4."<input value=$row4[0]$row4[1]</input>";
   }

?>

Here is the html textbox:

<label for="txtfield">Project Number</label>
            <!--<input type="text" id="reqtxtfield" name="projectnumber" 
value="<?php  ?>" readonly/>-->
              <?php echo $options4;?>

PHP:

<?php
  $query_5 = "SELECT MAX(ProjectNumber) FROM tblProjects;";
  $result_5 = mysqli_query($conn, $query_5);
  $row_5 = mysqli_fetch_array($result_5);
  $nextproject=$row_5['MAX(ProjectNumber)']+1;
?>

HTML:

<html>
  <form class="myform" action="<?php echo htmlspecialchars($_SERVER[" PHP_SELF "]);?>" method="post">
  <label for="txtfield">Project Number</label>
     <input type="text" id="reqtxtfield" name="projectnumber" value="<?php echo $nextproject ?>" readonly/><br>

After running successful insert query:

echo "<meta http-equiv='refresh' content='0'>";  //REFRESH PAGE TO UPDATE PROJECT NUMBER

But it would look like how you had it but instead of '1' inside the box it would display '19000' and there would be nothing outside of the box other than the label "Project Number". As far as i'm aware you can assign a value to the text box, regardless of whatever the input is. I would like it to display the value from one field name but actually contain the value from a different field name. Both are in the same table of course.

OK - gotcha. Unfortunately, you cannot do that. A textbox can only have one value and the user is always free to change that value, even if you make it read-only. You can test that out by using the developer toolbar in your browser. Probably a good time to mention that all user input should be considered dangerous and you should never trust it. Once they have submitted the form you need to verify it.

change value through developer toolbar

What I would recommend in your case is to use a hidden <input> which contains the value you actually want to submit; projectnoid. You can then display the Project Number in any manner you choose.

<form>
        <h1>Project Number: 19000</h1>
        <input type="hidden" name="projectnoid" value="1">
        <input type="submit" name="submit">
    </form>

To generate this, you would:

<?php
while($row4 = mysqli_fetch_row($result4)){

    $projectnoid = $row[0];
    $projectNumber = $row[1];

    echo '<h1>' . $projectNumber . '</h1>';
    echo '<input type="hidden" name="projectnoid" value="'. $projectnoid .'">
}

</div>