Date wrong in PHP function - php

Question

I have the following code and I'm able to add to today's date, but if the existing date is before today it still returns today's date. MySQL data is stored as a y-m-d string.
$date = date('Y-m-d');
$oldate = "SELECT date FROM signup WHERE user='$user'";
$result1 = mysqli_query($connection, $oldate) or die(mysqli_error($connection));
if (strtotime($result1) < $date) {
$date1 = date('Y-m-d', strtotime("+$months months", strtotime($date)));
} else {
$date1 = date('Y-m-d', strtotime("+$months months", strtotime($result1)));
}

Answer 1

You are comparing timestamp value ($result1) with string $date1.You need to cast your $date1 to timestamp as well. Change your if condition to make it work as follow:
if(strtotime($result1)<strtotime($date))
{
....
}
else
{
.....
}

Answer 2

The reason you're above code isn't working is because $result1 won't be a date. mysqli_query will return an instance of mysqli_result when you've performed a successful select query.
http://php.net/manual/en/mysqli.query.php :
Returns FALSE on failure. For successful SELECT, SHOW, DESCRIBE or EXPLAIN queries mysqli_query() will return a mysqli_result object. For other successful queries mysqli_query() will return TRUE.
You can use mysqli_fetch_assoc to get the information you want:
$row = mysqli_fetch_assoc($result1);
$rowDate = $row['date'];
Also, as Prada pointed out you can't not compare dates in the way you have in your question, however, you could do something like:
if (strtotime($rowDate) < strtotime($date))
Alternatively, you could use DateTime and have something like:
$oldate = "SELECT date FROM signup WHERE user='$user'";
$result1 = mysqli_query($connection, $oldate) or die(mysqli_error($connection));
$row = mysqli_fetch_assoc($result1);
$now = new DateTime;
$date = new DateTime($row['date']);
$date1 = $date < $now
? $now->modify("+$months months")->format('Y-m-d')
: $date->modify("+$months months")->format('Y-m-d');
Hope this helps!