Good day all, I have the form shown below but I noticed that whenever the form input couldn't get inserted in the database, an error message is shown which is ok by me but how will I do it to make the previously filled data appear in their respective fields when I click the back button? Please note that I use $_SESSION and in the index page that processes the form, I used "include" to display the error message. Thanks for your anticipated contribution/solution.

The form:
Code:
<form action="index.php" method="post">
        <fieldset>
    <legend>Personal Information</legend>
    
    <div class="row">
        <div class="large-3 columns">Title</div>
        <div class="large-3 columns"><input type="text" name="title" id="title" <?php if (isset($title)) { echo 'value="' . htmlentities($title, ENT_COMPAT, 'UTF-8') . '"'; } ?> /></div>
        <div class="large-3 columns">First Name</div>
        <div class="large-3 columns"><input type="text" name="firstName" id="firstName" <?php if (isset($firstName)) { echo 'value="' . htmlentities($firstName, ENT_COMPAT, 'UTF-8') . '"'; } ?> /></div>
       </div>
       
       <div class="row">
        <div class="large-3 columns">Last Name</div>
        <div class="large-3 columns"><input type="text" name="lastName" id="lastName" <?php if (isset($lastName)) { echo 'value="' . htmlentities($lastName, ENT_COMPAT, 'UTF-8') . '"'; } ?> /></div>
        <div class="large-3 columns">Middle Name</div>
        <div class="large-3 columns"><input type="text" name="middleName" id="middleName" <?php if (isset($middleName)) { echo 'value="' . htmlentities($middleName, ENT_COMPAT, 'UTF-8') . '"'; } ?> /></div>
       </div>
        
        <div class="row">
        <div class="large-3 columns">Gender</div>
        <div class="large-3 columns"><select name="gender">
              <option value="">Select Your Gender</option>
              <option value="Male" <?php if(isset($gender) && $gender == 'Male') echo 'selected';  ?> >Male</option>
              <option value="Female" <?php if(isset($gender) && $gender == 'Female') echo 'selected';  ?> >Female</option>
              </select></div>
        <div class="large-3 columns">Marital Status</div>
        <div class="large-3 columns"><select name="maritalStatus">
        <option value="">Select Your Status</option>
        <option value="Married" <?php if(isset($maritalStatus) && $maritalStatus == 'Married') echo 'selected';  ?> >Married</option>
        <option value="Single" <?php if(isset($maritalStatus) && $maritalStatus == 'Single') echo 'selected';  ?> >Single</option>
        <option value="Widowed" <?php if(isset($maritalStatus) && $maritalStatus == 'Widowed') echo 'selected';  ?> >Widowed</option>
        <option value="Separated" <?php if(isset($maritalStatus) && $maritalStatus == 'Separated') echo 'selected';  ?> >Separated</option>
        <option value="Divorced" <?php if(isset($maritalStatus) && $maritalStatus == 'Divorced') echo 'selected';  ?> >Divorced</option>
        </select></div>
       </div>
        
        <div class="row">
        <div class="large-3 columns">Date of Birth</div>
        <div class="large-3 columns"><input type="text" name="dateOfBirth" id="datePicker" <?php if (isset($dateOfBirth)) { echo 'value="' . htmlentities($dateOfBirth, ENT_COMPAT, 'UTF-8') . '"'; } ?> /></div>
        <div class="large-3 columns">Wedding Anniversary</div>
        <div class="large-3 columns"><input type="text" name="weddingAnniversary" id="datePicker2" <?php if (isset($weddingAnniversary)) { echo 'value="' . htmlentities($weddingAnniversary, ENT_COMPAT, 'UTF-8') . '"'; } ?> /></div>
       </div>
       
       <div class="row">
        <div class="large-3 columns">Occupation</div>
        <div class="large-3 columns"><input type="text" name="occupation" id="occupation" <?php if (isset($occupation)) { echo 'value="' . htmlentities($occupation, ENT_COMPAT, 'UTF-8') . '"'; } ?> /></div>
        <div class="large-3 columns">State of Origin</div>
        <div class="large-3 columns"><input type="text" name="stateOfOrigin" id="stateOfOrigin" <?php if (isset($stateOfOrigin)) { echo 'value="' . htmlentities($stateOfOrigin, ENT_COMPAT, 'UTF-8') . '"'; } ?> /></div>
       </div>
       
       <div class="row">
        <div class="large-3 columns">Nationality</div>
        <div class="large-3 columns"><input type="text" name="nationality" id="nationality" <?php if (isset($nationality)) { echo 'value="' . htmlentities($nationality, ENT_COMPAT, 'UTF-8') . '"'; } ?> /></div>
        <div class="large-3 columns">&nbsp;</div>
        <div class="large-3 columns">&nbsp;</div>
       </div>
       </fieldset>

       <div class="row">
       <div class="large-7 columns">
       <input type="hidden" name="id" <?php if (isset($id)) { echo 'value="' . htmlentities($id, ENT_COMPAT, 'UTF-8') . '"'; } ?> />
       <input type="reset" name="button"  value="Reset"  class="button round"/>
        <input type="submit" name="button" value="Register New Member" class="button round"/>
      </div>
      <div class="large-5 offset-5 columns">&nbsp;</div>
       </div>
     </form>

The index.php

PHP Code:
if(isset($_POST['button']) && $_POST['button'] == 'Register New Member')
{

$conn DatabaseManager::getConnection();
try
{
$sql "INSERT INTO members ( affiliation, title, firstName, middleName, lastName, gender, maritalStatus, occupation, stateOfOrigin, nationality ) 
                     VALUES ( :affiliation, :title, :firstName, :middleName, :lastName, :gender, :maritalStatus, :occupation, :stateOfOrigin, :nationality)"
;

    
    
$st $conn->prepare $sql );
        
$st->bindValue":affiliation"$affiliation);
    
$st->bindValue":title"$_POST['title'], PDO::PARAM_STR );
    
$st->bindValue":firstName"$_POST['firstName'], PDO::PARAM_STR );
    
$st->bindValue":middleName"$_POST['middleName'], PDO::PARAM_STR );
    
$st->bindValue":lastName"$_POST['lastName'], PDO::PARAM_STR );
    
$st->bindValue":gender"$_POST['gender'], PDO::PARAM_STR );
    
$st->bindValue":maritalStatus"$_POST['maritalStatus'], PDO::PARAM_STR );
    
$st->bindValue":occupation"$_POST['occupation'], PDO::PARAM_STR );
    
$st->bindValue":stateOfOrigin"$_POST['stateOfOrigin'], PDO::PARAM_STR );
    
$st->bindValue":nationality"$_POST['nationality'], PDO::PARAM_STR );

$st->execute();
$conn null;
}
catch (
PDOException $e)
{
$error 'There was an error while registering the Member, Please try again later.' $e->getMessage();
include 
'error.html.php';
exit();
}

if(
$st->rowCount() == 1)
  {
  
$output 'New Member successfully registered';
  include 
'output.html.php';
  exit();
  }
else
{
$error 'Unable to perform your request now, Please try again later.';
include 
'error.html.php';
exit();

       }    
   
  }