Select smallest and biggest value of an object - php

Question

I'm trying to get the smallest value of start and the biggest value of end outoff the object below. The object is an result of a sql script.
object(CI_DB_mysql_result)[18]
public 'conn_id' => resource(54, mysql link persistent)
public 'result_id' => resource(61, mysql result)
public 'result_array' =>
array (size=0)
empty
public 'result_object' =>
array (size=3)
0 =>
object(stdClass)[16]
public 'id' => string '601' (length=3)
public 'scheduled' => string '0' (length=1)
public 'start' => string '2014-10-17 06:00:00' (length=19)
public 'end' => string '2014-10-17 11:00:00' (length=19)
1 =>
object(stdClass)[19]
public 'id' => string '602' (length=3)
public 'scheduled' => string '0' (length=1)
public 'start' => string '2014-10-17 18:00:00' (length=19)
public 'end' => string '2014-10-17 19:30:00' (length=19)
2 =>
object(stdClass)[20]
public 'id' => string '603' (length=3)
public 'scheduled' => string '1' (length=1)
public 'start' => string '2014-10-17 11:00:00' (length=19)
public 'end' => string '2014-10-17 18:00:00' (length=19)
public 'custom_result_object' =>
array (size=0)
empty
public 'current_row' => int 0
public 'num_rows' => int 3
public 'row_data' => null
In this case the smallest value of start = '2014-10-17 06:00:00' and the biggest value of end = '2014-10-17 19:30:00'. So the result I'm looking for looks like this:
$smallest_start_value = '2014-10-17 06:00:00';
$biggest_end_value = '2014-10-17 19:30:00';
How should the code look like, in order to compute this result?
Function:
function unschedule_resource() {
$event_id = 4;//$_POST['event_id'];
$event_start = '2014-10-17 11:00:00';//$_POST['event_start'];
$event_end = '2014-10-17 18:00:00';//$_POST['event_end'];
// Get resource id
$this->db->select('
event.resource_id'
);
$this->db->from('promo_manager.event');
$this->db->where('event.id =', $event_id);
$data = $this->db->get();
foreach ($data->result() as $row) {
echo $row->resource_id . "<br>";
$resource_id = $row->resource_id;
}
// Get resource events to unschedule
$this->db->select('
resource_calendar.id,
resource_calendar.scheduled,
resource_calendar.start,
resource_calendar.end'
);
$this->db->from('promo_manager.resource_calendar');
$this->db->where('resource_calendar.resource_id =', $resource_id);
$this->db->where('resource_calendar.start =', $event_start);
$this->db->where('resource_calendar.end =', $event_end);
$this->db->or_where('resource_calendar.end =', $event_start);
$this->db->or_where('resource_calendar.start =', $event_end);
$data = $this->db->get();
$lowest_value = null;
$highest_value = null;
foreach ($data as $the_key => $the_value) {
if ($the_key == 'start') {
if ($lowest_value === null) {
$lowest_value = $the_value;
}
if ($the_value < $lowest_value) {
$lowest_value = $the_value;
}
}
}
//echo $lowest_value;
var_dump ($lowest_value) ;
}

Answer 1

The code of Sam should look like this:
$lowest_value = null;
$highest_value = null;
foreach($data as $obj) { //$data should be the array containing the result objects.
$start = $obj->start;
$end = $obj->end;
if ($lowest_value === null)
$lowest_value = $start;
else
if ($lowest_value > $start)
$lowest_value = $start;
if ($highest_value === null)
$highest_value = $end;
else
if ($highest_value < $end)
$highest_value = $end;
}
can be shortened to :
if ($lowest_value === null || $lowest_value > $start)
$lowest_value = $start;
if ($highest_value === null || $highest_value < $end)
$highest_value = $end;
Both values can be generated within one iteration without problems. Keep in mind that the < and > works in the case you keep the date formated as given. Otherwhise you would need to use date-functionality to compare the dates.
You could also use MySQL to query directly for the Min/Max values using the Aggregation methods Min or Max: http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html
(If you don't need each object to be loaded this will be faster)

Answer 2

I'm not sure if there's a way you couldn't do this in the select statement or not, I'll assume not. Get your result object into an array. This is super basic but should get the job done.
$lowest_value = null;
$highest_value = null;
foreach(result_object as $the_key => $the_value) {
if($the_key == 'start') {
if($lowest_value === null) {
$lowest_value = $the_value;
}
if(the_value < $lowest_value) {
$lowest_value = $the_value;
}
}
}
Do a second check for the end value just changing the operator