Why does my function don't add proper data - php

Question

I'm trying to create an array of data which will be grouped by time (field_time_value).
This is the raw result of SQL query and I operate on this data ($query):
This is the result I'd like to have (desired) - all the closed keys has an empty value:
This is what I have right now (look at the value on [15.15][data][1][data] - it's empty and according to data in $query it should be filled in, as above), all the closed keys has an empty value:
This is the code I'm using:
$days = array(
1 => t('Monday'),
2 => t('Tuesday'),
3 => t('Wednesday'),
4 => t('Thursday'),
5 => t('Friday'),
6 => t('Saturday'),
7 => t('Sunday'),
);
foreach ($query as $key => $value) {
foreach($days as $day_key => $day_name) {
if ($value->field_day_value == $day_key) {
$rows[$value->field_time_value]['data'][$day_key] = array('data' => 'Day: '.$value->field_day_value.' Hour: '.$value->field_time_value);
} else {
$rows[$value->field_time_value]['data'][$day_key] = array('data' => 'empty');
}
}
}
What am I doing wrong?

Answer 1

Don't bother anymore, I get the problem. There should be one more condition which will prevent from overriding data in my array:
foreach ($query as $key => $value) {
foreach($days as $day_key => $day_name) {
if ($value->field_day_value == $day_key) {
$rows[$value->field_time_value]['data'][$day_key] = array('data' => 'Day: '.$value->field_day_value.' Hour: '.$value->field_time_value);
} else {
if (!isset($rows[$value->field_time_value]['data'][$day_key])) {
$rows[$value->field_time_value]['data'][$day_key] = array('data' => 'empty');
}
}
}
}