Can't get all dates between two dates php

This scripts needs to collect the data from the previous site and needs to send the data to my database:

<?php
$user = $_POST["user"];
$begindate= $_POST["begindate"];
$enddate= $_POST["einddatum"];
$connect = new mysqli("localhost", "root", "", "shit");

if ($begindate== $enddate) {
    $sql = "INSERT INTO usershit (user,date) VALUES ('$user','$begindate')";
    mysqli_query ($connect, $sql);
} elseif ($begindate!= $enddate){
do {
    $begindate= strtotime('+1 day',$begindate); 
    $sql = "INSERT INTO usershit (user,date) VALUES ('$user','$begindate')";
    mysqli_query ($connect, $sql);
} while ($begindate< $enddate);
}
?>

If u know how to fix it with something else than do while it's fine as well.