if (isset($_POST['musteriac'])) {

$sor = $db->prepare("SELECT musteri_mail FROM musteri WHERE musteri_mail=:mail");
$sor->execute([
'mail' => $_POST['musteri_mail']
]);
if (!$sor->rowCount()) {
$musteriac=$db->prepare("INSERT INTO musteri SET
musteri_mail=:mail,
musteri_name=:name,
musteri_sifre=:sifre

");
$musteriac->execute(array(
'mail' => $_POST['musteri_mail'],
'name' => $_POST['musteri_name'],
'sifre' => $_POST['musteri_sifre']
));

if ($musteriac) {
header("location:/login");
} else{
echo "Başarısız..";
exit;
}
}
}