How to insert HTML datetime local input into MYSQL table datetime column using PHP?

Question

for($i=0;$i<=feof($getdata);$i++)
{
if (filter_var($data[$i][1], FILTER_VALIDATE_EMAIL)){
echo $data[$i][1];
$email=$data[$i][1];
$conn = mysqli_connect($dbhost,$dbuser,$dbpass, $dbname);
if ($conn->connect_error) {
  die("Connection failed: " . $conn->connect_error);
}
$sql ="INSERT INTO promo_user (uid,name,email) VALUES (,'', '$email')";
mysqli_query($sql,$conn);
mysqli_close($conn);

I am using the above code but there is something wrong with it,whenever i run the code the echo is working fine but the content does go into sql table

Please help