Insert

<?php
if(isset($_POST['insert'])){
    $dname = $_POST['dname'];
    $dnum = $_POST['dnum'];
    $mgr_ssn = $_POST['mgr_ssn'];
    $date = $_POST['date'];
    $sql = "INSERT INTO `department`(`Dname`, `Dnumber`, `Mgr_ssn`, `Mgr_start_date`) VALUES ('$dname',$dnum,$mgr_ssn,'$date')";
    if(mysqli_query($conn,$sql)){
        echo "<script>alert('Data Inserted ')</script>";
    }else{
        echo "<script>alert('There Is Problem !')</script>";
    }
}
?>