Error in storing the records in database - php

Question

The following code for create edit form to update records. If I give all field it update correctly if I didn't change image it does not update the record. I want to update record without change image and also I want to update records by only changing the image.
<section id="main-content">
<section class="wrapper">
<h3><i class="fa fa-angle-right"></i> About Components</h3>
<!-- BASIC FORM ELELEMNTS -->
<div class="row mt">
<div class="col-lg-12">
<div class="form-panel">
<h3><i class="fa fa-angle-right"></i> Team Update</h3>
<form class="form-horizontal style-form" enctype="multipart/form-data" method="post">
<div class="form-group">
<label class="col-sm-2 col-sm-2 control-label">Title</label>
<div class="col-sm-10">
<textarea type="text" name="Title" class="form-control" required><?php echo $img['a_title']; ?></textarea>
</div>
</div>
<div class="form-group">
<label class="col-sm-2 col-sm-2 control-label">Description</label>
<div class="col-sm-10">
<textarea type="text" name="Description" class="form-control" required><?php echo $img['a_description']; ?></textarea>
</div>
</div>
<div class="form-group">
<label class="col-sm-2 col-sm-2 control-label">Picture</label>
<div class="col-sm-10">
<div class="clear" id="im">
<?php echo "<img src='/myproject/cp/image/".$img['a_image']."'height='50' width='50' >"; ?>
<button type="button" id="remove" >remove</button>
</div>
<div id="browse" style="display:none;">
<input type="file" name="imageupload" value="imageupload" />
</div>
</div>
</div>
<div class="form-group">
<label class="col-sm-2 col-sm-2 control-label"></label>
<div class="col-sm-10">
<input class="btn btn-theme" id="focusedInput" type="submit" name="submit" value="Submit" />
</div>
</div>
<a class="btn btn-primary" href="about.php">
<span>List view</span>
</a>
</form>
</div>
</div><!-- col-lg-12-->
</div><!-- /row --><?php
if(isset($_POST['submit']))
{
$var=$_GET['a_id'];
$file=$_SERVER['DOCUMENT_ROOT'].'myproject/cp/image/'.$img['a_image'];
unlink($file);
$var1=$_POST['Title'];
$var2=$_POST['Description'];
$image=$_FILES['imageupload']['name'];
$root=$_SERVER['DOCUMENT_ROOT'].'/myproject/cp/image/';
$file_exts = array("jpg", "bmp", "jpeg", "gif", "png");
$expo=explode(".", $_FILES["imageupload"]["name"]);
$upload_exts = end($expo);
if ((($_FILES["imageupload"]["type"] == "image/gif")|| ($_FILES["imageupload"]["type"] == "image/jpeg")|| ($_FILES["imageupload"]["type"] == "image/png")|| ($_FILES["imageupload"]["type"] == "image/jpg"))&& ($_FILES["imageupload"]["size"] < 2000000)&& in_array($upload_exts,$file_exts))
{
if ($_FILES["imageupload"]["error"] > 0)
{
echo "Return Code: " . $_FILES["imageupload"]["error"] . "<br>";
}
else
{
$image= rand(0,9999).'.'.$upload_exts;
move_uploaded_file($_FILES["imageupload"]["tmp_name"],$root.$image);
$sql=mysql_query("UPDATE about SET a_title='".$var1."',a_description='".$var2."',a_image='".$image."' WHERE a_id='".$var."'") or die(mysql_error());
echo "<meta http-equiv=refresh content=\"0; URL=about.php\">";
}
}
}
?>

Answer 1

As you said in comment , when you save the edits all other details get saved but your image get's removed even if you haven't changed it , clearly it's your php code , even before checking that if you are submiting an image or not you already doing an unlink on it , you have to use the edit below :
<?php
if(isset($_POST['submit']))
{
$var=$_GET['a_id'];
$file_del =$_SERVER['DOCUMENT_ROOT'].'myproject/cp/image/'.$img['a_image'];
$var1=$_POST['Title'];
$var2=$_POST['Description'];
$image=$_FILES['imageupload']['name'];
$root=$_SERVER['DOCUMENT_ROOT'].'/myproject/cp/image/';
$file_exts = array("jpg", "bmp", "jpeg", "gif", "png");
$expo=explode(".", $_FILES["imageupload"]["name"]);
$upload_exts = end($expo);
if ((($_FILES["imageupload"]["type"] == "image/gif")|| ($_FILES["imageupload"]["type"] == "image/jpeg")|| ($_FILES["imageupload"]["type"] == "image/png")|| ($_FILES["imageupload"]["type"] == "image/jpg"))&& ($_FILES["imageupload"]["size"] < 2000000)&& in_array($upload_exts,$file_exts))
{
if ($_FILES["imageupload"]["error"] > 0)
{
echo "Return Code: " . $_FILES["imageupload"]["error"] . "<br>";
}
else
{
unlink($file_del);
$image= rand(0,9999).'.'.$upload_exts;
move_uploaded_file($_FILES["imageupload"]["tmp_name"],$root.$image);
$sql=mysql_query("UPDATE about SET a_title='".$var1."',a_description='".$var2."',a_image='".$image."' WHERE a_id='".$var."'") or die(mysql_error());
echo "<meta http-equiv=refresh content=\"0; URL=about.php\">";
}
}
}