current week if date() function and date from mysqli - php

Question

I have a table containing the following:
StartWeek | StartName |
2012-07-16 | 1 |
What I want to do. Is take the starting week, the current date, and calculate how much time has passed between then and now.
So far I have this:
function getCurrentWeekName() {
$mysqli = new mysqli(DB_SERVER, DB_USER, DB_PASSWORD, DB_NAME);
if (!$mysqli) {
die('There was a problem connecting to the database.');
}
else {
date_default_timezone_set('UTC');
echo "Current date: ".$current_date = date('Y-m-j')."<br>";
$mysqli = new mysqli(DB_SERVER, DB_USER, DB_PASSWORD, DB_NAME);
$query = $mysqli->prepare("SELECT StartWeek FROM Week");
$query->execute();
$query->bind_result($start_date);
while ($query->fetch()){
$start_date = $start_date;
}
echo "start date: ".$start_date."<br>";
echo "time passed: ".$time_passed = strtotime($current_date) - strtotime($start_date)."<br>";
echo "number of days since start: ".$num_of_days = ceil($time_passed/(86400*7))."<br>";
$week_num = ceil($num_of_days/7);
$query = $mysqli->prepare("SELECT StartName FROM Week");
$query->execute();
$query->bind_result($start_name);
while ($query->fetch()){
echo "Start name: ".$start_name = $start_name."<br>";
}
$week_num = $start_name + $week_num;
echo "Week Number: ".$week_num;
}
$mysqli->close();
}
The problem is, this returns the following information:
Current date: 2013-03-18
start date: 2012-07-16
time passed: -1342394787
number of days since start: -2219
Start name: 1
Week Number: -316
So clearly I'm doing it wrong. I think it must be something to do with my time passed calculation, maybe I shouldn't be using strtotime. Can anybody help?

Answer 1

If you're looking for just a difference in days, you can do it directly in MySQL:
SELECT DATEDIFF(now(), StartDate) AS diff_in_days
for other differences, e.g. hours, you can also do things like
SELECT unix_timestamp(now()) - unix_timestamp(start_date) AS seconds

Answer 2

you can do this with php date-diff => http://php.net/manual/en/function.date-diff.php
Check if this you can use:
//replace the values for $startDate and $endDate:
$startDate = strtotime($startDate);
$endDate = strtotime($endDate);
$intervalo = date_diff(date_create($startDate), date_create($endDate));
$out = $intervalo->format("Years:%Y,Months:%M,Days:%d,Hours:%H,Minutes:%i,Seconds:%s");
if(!$out_in_array)
return $out;
$a_out = array();
array_walk(explode(',',$out),
function($val,$key) use(&$a_out){
$v=explode(':',$val);
$a_out[$v[0]] = $v[1];
});
print_r($a_out);