php - How do I display echo after form submit on return to html page? -

this show echo on blank white page.

$existsquery = "select count(*) count entry emailaddress '".$_post[emailaddress]."'"; $existsresult = mysqli_query($con, $existsquery);  if($existsresult->fetch_object()->count > 0) {     echo "email exist";     /* header('index.html?email=exists'); */ } 

i want show echo under submit button on main html page. using url way , how do it?

is using url way , how do it?

i think that's solution, code this:

$existsquery = "select count(*) count entry emailaddress '".$_post[emailaddress]."'"; $existsresult = mysqli_query($con, $existsquery);  if($existsresult->fetch_object()->count > 0) {     header('index.html?email=exists'); } 

and can right below button submit button in form:

<?= if (isset($_get["email"]) && $_get["email"] == "exists") { echo "email exists"; } ?>