如果出现错误声明，则更容易在php中的文本字段中保留数据

I have a simple xhtml form with textboxes asking the user for their name, id, address etc. I have to use php to validate the data. For example in the ID field exactly 6 numerical values are allowed, if thats not the case, it shows an error to the user asking them to fix it. What i want do is, when the user clicks submit with the incorrect data, i want to keep the data in the field when the error shows up. I am currently doing that by:-

 <td><label for="customerid">*Customer ID: </label></td>
    <td><input type="text" value="
<?php if(($_POST['customerid'] != $id) || ($_POST["customerfname"] != $fname) 
||    ($_POST["customerlname"] != $lname)){echo $_POST['customerid'];} ?>"

id="customerid" name="customerid"/>

I have just been modyifying that statement for all textboxes but as you can imagine it will get a little complicated if i have to do that for 10 boxes. i was wondering if it was an easier way to do this.

bold UPDATED

<td> <select name="state" id="state"  value="<?php echo (isset($_POST["state"]) ?  : ''); ?>"> 
    <option value="--">--</option>
    <option value="ACT">ACT</option>
    <option value="NSW">NSW</option>
    <option value="NT">NT</option>
    <option value="QLD">QLD</option>
    <option value="SA">SA</option>
 </select>
</td>

Something like this?

<input type="text" name="customerid" value="<?php echo (isset($_POST['customerid']) ? $_POST['customerid'] : ''); ?>">

Update - run your checks before the form is re-generated

<?php

if(($_POST['customerid'] != $id) || ($_POST["customerfname"] != $fname) || ($_POST["customerlname"] != $lname))
{
    // do nothing
}
else
{
    $_POST['customerid'] = '';
}

?>

<input type="text" name="customerid" value="<?php echo (isset($_POST['customerid']) ? $_POST['customerid'] : ''); ?>">

A few things you can do here either separately, or in some combination:

1. Submit the form via AJAX
2. Do validation in Javascript before handing it off to the server (this will catch most of the errors a user might encounter)
3. Keep the submitted values in the $_SESSION array and just echo them into the field if they are set. ex <input type='text' value='<?php echo $_SESSION['myVal'] || '';?>'></input>

what are those statements?

$_POST['customerid'] != $id

you can make $fields array to store labels an $errors array to place errors in and then just

<?php $fields = array ('customerId' => '*CustomerID'); ?>

<?php  // validation   ?>

<?php foreach($fields as $name => $label): ?>

<td><label for="<?php echo $name ?>"><?php echo $label?>: </label></td>
<td>
<input type="text" value="" id="<?php echo $name ?>" name="<?php echo $name ?>">

<?php if(isset($errors[$name])): ?>
  <?php echo $errors[$name] ?>
<?php endif; ?>
</td>


<?php endforeach; ?>

You could also add html validation to the form to stop the user from submitting empty form by adding "required" attribute to inputs (<input required ... >) or the "pattern" attribute