username not exists yet it says username already exists - php

Question

I am using following codes to prevent entry of duplicate username in the database but it always says "username already exists" through the particular username not exists in the database. I can not understand where I am doing wrong. Thanks in advance.
$ImageName = $ImageDir.$image_tempname;
$query = mysqli_query($conn, "SELECT * FROM usernames WHERE username='".$username."'");
$rows = mysqli_num_rows($query);
if (move_uploaded_file($_FILES['image']['tmp_name'],
$ImageName)) {
//get info about the image being uploaded
list($width, $height, $type, $attr) = getimagesize($ImageName);
//**insert these new lines
if ($type > 3) {
echo "Sorry, but the file you uploaded was not a GIF, JPG, or " .
"PNG file.<br>";
echo "Please hit your browser's 'back' button and try again.";
}
elseif ($rows > 0){
echo "email already exists";
}
else {
//image is acceptable; ok to proceed
//**end of inserted lines
//insert info into image table
$insert = "INSERT INTO xyz (.......)
VALUES (........)";
$insertresults = mysqli_query($insert); //order executes
if($insertresults)
{
header ("Location:https://www.getalifepartner.com/free-matrimonial-site/upload_success.php");
}

Answer 1

Here is one way
$query = mysqli_query($con, "SELECT * FROM usernames WHERE username='$username'");
$res = mysqli_fetch_array($query);
if ($res['username'] == $username)
{
echo 'Username already in use, please choose another one.';
}
else
{
// username not in use
}
Here is another way
$query = mysqli_query($con, "SELECT * FROM usernames WHERE username='$username'");
$rows = mysqli_num_rows($query);
if ($rows > 0)
{
echo 'Username already in use, please choose another one.';
}
else
{
// username not in use
}
UPDATE TO ORIGINAL QUESTION
$ImageName = $ImageDir.$image_tempname;
$query = mysqli_query($conn, "SELECT * FROM usernames WHERE username='$username'");
$rows = mysqli_num_rows($query);
if (move_uploaded_file($_FILES['image']['tmp_name'], $ImageName))
{
//get info about the image being uploaded
list($width, $height, $type, $attr) = getimagesize($ImageName);
//**insert these new lines
if ($type > 3)
{
echo "Sorry, but the file you uploaded was not a GIF, JPG, or PNG file.<br>";
echo "Please hit your browser's 'back' button and try again.";
}
}
elseif ($rows > 0)
{
echo "Email already exists.";
}
else
{
//image is acceptable; ok to proceed
//**end of inserted lines
//insert info into image table
}