I my code is vulnerable to sql injection Its hardly coded? [closed]

Is my code is vulnerable to sql Injection.It is hardly coded

if (isset($_POST['submit'])) {
    $content = strip_tags($_POST['cont'],'<h1>,<br>,<h2>,<h3>,<h4>,<strong>,<a>');
    $content_date = date('d-m-y');

    if (!empty($content)) {

        $check = "SELECT * FROM post WHERE user_id = ?";
        $stmt = $con->prepare($check);
        $stmt->bind_param("i",$my_id);

        $stmt->execute();

        $stmt->store_result();
        $numberofrows = $stmt->num_rows;

        if ($numberofrows == 1) {
            $up = "UPDATE post SET content = ? , con_date = ? WHERE user_id = ? ";
            $stmtup = $con->prepare($up);
            $stmtup->bind_param("ssi",$content,$content_date,$my_id);
            $stmtup->execute();
            $stmtup->close();
            echo "<script>alert('Information Updated')</script>";
            echo "<meta http-equiv='refresh' content='0'>";


        }else{
            $in = "INSERT INTO post(user_id,content,con_date) VALUES (?,?,?) ";
            $stmtin = $con->prepare($in);
            $stmtin->bind_param("iss",$my_id,$content,$content_date);
            $stmtin->execute();
            $stmtin->close();
            echo "<script>alert('Information Updated')</script>";
            echo "<meta http-equiv='refresh' content='0'>";

        }
    }else{
        echo "<script>alert('Please fill the Fields')</script>";
        exit();
    }
}