PHP中MySQL的两次时差

Question

I have a database table build in this structure.

ID      - INT
addDate - DateTime
sunrise - Time
sunset  - Time

The Datasets look like

Now I'm trying to retrieve the difference in minutes between

SELECT addDate, TIMESTAMPDIFF(MINUTE, sunrise, sunset) AS duration FROM SunData WHERE date(addDate) BETWEEN curdate() - interval 7 day and curdate() ORDER BY addDate ASC

The results I'm getting NULL in every row for duration.

Code to display these values

$date = date("Y-m-d H:i:s", strtotime(str_replace('-','/',$row->addDate)));
$duration = $row->duration / 60;

echo "Dauer: " . $duration . "Stunden
";

Why are the values getting less and less? Is my query correct?

Answer 1

You are ordering by addDate in the ascending order. You are taking the difference between now() and addDate. Ascending order means addDate keeps getting bigger, so the difference between addDate and now() keeps getting smaller.