如何使用php减去名称列中具有相同条目的时间列的最小值和最大值

Question

$sqlquery1="select max(obj)- min(obj) FROM `$v` WHERE name='$n'";
$res=mysqli_query($conn1,$sqlquery1);
if($res==FALSE)
{
  echo "failed";
}
for ($resArray = array(); $row = mysqli_fetch_assoc($res); $resArray[] =$row);
$arr=array();
$arr= call_user_func_array('array_merge', $resArray);
print_r($arr);

它返回

Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => ) 
Array ( [max(obj)- min(obj)] => )