change image or keep de old one with php form

Question

I am doing a db update form and i have 3 input files for images

<div class="row d-flex justify-content-around">
                    <div class="loadImg col-3 m-1 overflow-hidden">
                        <input type="file" id="fileUpload1" name="fileUpload1" accept=".jpg, .jpeg, .png"/>
                        <div class="mt-2" id="showImg1">
                            <img src="<?= $house['img1'] ?>" width="200" height="150"/>
                        </div>
                    </div>
                    <div class="loadImg col-3 m-1 overflow-hidden">
                        <input type="file" id="fileUpload2" name="fileUpload2" accept=".jpg, .jpeg, .png"/>
                        <div  class="mt-2"  id="showImg2">
                            <img src="<?= $house['img2'] ?>" width="200" height="150"/>
                        </div>
                    </div>
                    <div class="loadImg col-3 m-1 overflow-hidden">
                        <input type="file" id="fileUpload3" name="fileUpload3" accept=".jpg, .jpeg, .png"/>
                        <div class="mt-2" id="showImg3">
                            <img src="<?= $house['img3'] ?>" width="200" height="150"/>
                        </div>
                    </div>
                </div>

the showImg div get the old img on the database or show a preview for the new one with js... My question is if I change only one or two files how to keep the old one unchanged? because when I post my form the unchanged img get the path 'public/img/' !!! I am sure that you guys have the answer ;)

THX

my update php request

public function modifyMyHouse()
{
    $conn = $this->connect();
    if (isset($_POST['modifyHouse'])) {
        $author_id = $_SESSION['id'];
        $zipCode = htmlspecialchars($_POST['houseZipCode']);
        $city = htmlspecialchars($_POST['houseCity']);
        $region = htmlspecialchars($_POST['houseRegion']);
        $beds = htmlspecialchars($_POST['beds']);
        $dateFrom = htmlspecialchars($_POST['dateFrom']);
        $dateTo = htmlspecialchars($_POST['dateTo']);
        $equipment = htmlspecialchars($_POST['equipment']);
        $activity = htmlspecialchars($_POST['activity']);
        $descriptive = htmlspecialchars($_POST['descriptive']);
        $img1 = $_FILES['fileUpload1']['name'];
        $img2 = $_FILES['fileUpload2']['name'];
        $img3 = $_FILES['fileUpload3']['name'];
        $update = $conn->prepare("UPDATE myHousePost SET author_id = :author_id, zip_code = :zipCode, house_city = :city, house_region = :region, beds = :beds, date_from = :dateFrom, date_to = :dateTo, equipment = :equipment, activity = :activity, descriptive = :descriptive, img1 = :img1, img2 = :img2, img3 = :img3, post_date = Now()");
        $update->execute([':author_id'=>$author_id, ':zipCode'=>$zipCode, ':city'=>$city, ':region'=>$region, ':beds'=>$beds, ':dateFrom'=>$dateFrom, ':dateTo'=>$dateTo, ':equipment'=>$equipment, ':activity'=>$activity, ':descriptive'=>$descriptive, ':img1'=>'public/img/' . $img1 , ':img2'=>'public/img/' . $img2 , ':img3'=>'public/img/' . $img3]);
        if (!empty($update)) {
            move_uploaded_file($_FILES['fileUpload3']['tmp_name'], 'public/img/' . $img1);
            move_uploaded_file($_FILES['fileUpload3']['tmp_name'], 'public/img/' . $img2);
            move_uploaded_file($_FILES['fileUpload3']['tmp_name'], 'public/img/' . $img3);
            header('location:/home-switch-home/mon-annonce');
        } else{
            header('location:/home-switch-home/404');
        }
    }
}

Answer 1

UPDATE with answer

I just update Ronak Dhoot code!!!

public function modifyMyHouse()
{
    $conn = $this->connect();
    if (isset($_POST['modifyHouse'])) {
        $author_id = $_SESSION['id'];
        $zipCode = htmlspecialchars($_POST['houseZipCode']);
        $city = htmlspecialchars($_POST['houseCity']);
        $region = htmlspecialchars($_POST['houseRegion']);
        $beds = htmlspecialchars($_POST['beds']);
        $dateFrom = htmlspecialchars($_POST['dateFrom']);
        $dateTo = htmlspecialchars($_POST['dateTo']);
        $equipment = htmlspecialchars($_POST['equipment']);
        $activity = htmlspecialchars($_POST['activity']);
        $descriptive = htmlspecialchars($_POST['descriptive']);
        $img1 = $_FILES['fileUpload1']['name'];
        $img2 = $_FILES['fileUpload2']['name'];
        $img3 = $_FILES['fileUpload3']['name'];
        $updateSql = ("UPDATE myHousePost SET author_id = :author_id, zip_code = :zipCode, house_city = :city, house_region = :region, beds = :beds, date_from = :dateFrom, date_to = :dateTo, equipment = :equipment, activity = :activity, descriptive = :descriptive");
        $updateValues = ([':author_id'=>$author_id, ':zipCode'=>$zipCode, ':city'=>$city, ':region'=>$region, ':beds'=>$beds, ':dateFrom'=>$dateFrom, ':dateTo'=>$dateTo, ':equipment'=>$equipment, ':activity'=>$activity, ':descriptive'=>$descriptive]);
        if($_FILES['fileUpload1']['error'] !== 4) {
            $updateSql .= ",img1 = :img1 ";
            $updateValues[':img1'] = 'public/img/'. $img1;
        } 
        if($_FILES['fileUpload2']['error'] !== 4) {
            $updateSql .= ",img2 = :img2 ";
            $updateValues[':img2'] = 'public/img/'. $img2;
        } 
        if($_FILES['fileUpload3']['error'] !== 4) {
            $updateSql .= ",img3 = :img3 ";
            $updateValues[':img3'] = 'public/img/'. $img3;
        }
        $updateSql .= ",post_date = Now()";
        $update = $conn->prepare($updateSql);
        $update->execute($updateValues);
        if (!empty($update)) {
            move_uploaded_file($_FILES['fileUpload1']['tmp_name'], 'public/img/' . $img1);
            move_uploaded_file($_FILES['fileUpload2']['tmp_name'], 'public/img/' . $img2);
            move_uploaded_file($_FILES['fileUpload3']['tmp_name'], 'public/img/' . $img3);
            header('location:/home-switch-home/mon-annonce');
        } else{
            header('location:/home-switch-home/404');
        }
    }
}

Answer 2

As it is untouched $_FILES['fileUpload1']['name'] will be null

<?php
$img1 = $_FILES['fileUpload1']['name'];
$img2 = $_FILES['fileUpload2']['name'];
$img3 = $_FILES['fileUpload3']['name'];
$sql = "UPDATE myHousePost SET author_id = :author_id, zip_code = :zipCode, house_city = :city, house_region = :region, beds = :beds, date_from = :dateFrom, date_to = :dateTo, equipment = :equipment, activity = :activity, descriptive = :descriptive,";
$values = [':author_id'=>$author_id, ':zipCode'=>$zipCode, ':city'=>$city, ':region'=>$region, ':beds'=>$beds, ':dateFrom'=>$dateFrom, ':dateTo'=>$dateTo, ':equipment'=>$equipment, ':activity'=>$activity, ':descriptive'=>$descriptive, ':img1'=>'public/img/' . $img1 , ':img2'=>'public/img/' . $img2 , ];
if($img1 !== null) {
    $sql .= "img1 = :img1, ";
    $values[':img1'] = 'public/img/'. $img1;
} 
if($img2 !== null) {
    $sql .= "img2 = :img2, ";
    $values[':img2'] = 'public/img/'. $img2;
} 
if($img3 !== null) {
    $sql .= "img3 = :img3, ";
    $values[':img3'] = 'public/img/'. $img3;
}
$sql .= "post_date = Now()";
$update = $conn->prepare($sql);

$update->execute($values);
if (!empty($update)) {
    move_uploaded_file($_FILES['fileUpload3']['tmp_name'], 'public/img/' . $img1);
    move_uploaded_file($_FILES['fileUpload3']['tmp_name'], 'public/img/' . $img2);
    move_uploaded_file($_FILES['fileUpload3']['tmp_name'], 'public/img/' . $img3);
    header('location:/home-switch-home/mon-annonce');
} else{
    header('location:/home-switch-home/404');
}