$username = mysqli_real_escape_string($conn,$_POST['username']);
$sifre = mysqli_real_escape_string($conn,$_POST['sifre']);
$sifre = md5($sifre);
$sql1 = "SELECT * FROM users WHERE kullanici_adi='".$username."' AND sifre='".$sifre."'";

$username = $conn->real_escape_string($_POST['username']);
$sifre = $conn->real_escape_string($_POST['sifre']);
$sifre = md5($sifre);
$sql1 = "SELECT * FROM users WHERE kullanici_adi='".$username."' AND sifre='".$sifre."'";

<?php
if($_POST){
$username = mysqli_real_escape_string($conn,$_POST['username']);
$sifre = mysqli_real_escape_string($conn,$_POST['sifre']);
$sifre = md5($sifre);
$sql1 = "SELECT * FROM users WHERE kullanici_adi='".$username."' AND sifre='".$sifre."'";
$result1 = $conn->query($sql1 );
if($result1->num_rows > 0){
$_SESSION['oturum'] = TRUE;
$_SESSION['kullanici_adi'] = $username;
$sql2 = "SELECT * FROM users WHERE kullanici_adi='".$username."'";
$result2 = $conn->query($sql2);
if ($result2->num_rows > 0) {
while($row1 = $result2->fetch_assoc()) {
$_SESSION['yetki'] = $row1["yetki"];
}
}
if($_SESSION['yetki'] == 1) {
git("0","admin/dagitimlar.php");
} else {
git("0","user/panel.php");
}
}else {
echo '<div class="alert alert-danger" role="alert"><img draggable="false" class="emoji" alt="❌" src="//cdn.r10.net/emojis/html/274c.png"> || Lütfen bilgilerinizi kontrol ediniz.</div>';
}
}
?>