Filtering ARRAY and grabbing distinct entry - php

Question

Currently I am collecting a count of desktop and mobile devices... the count is coming back correctly based in the items total in the ARRAY. But, now I need to remove duplicates... Example user_id = 001 can have 10 entries for IOS ... so I would need to do something like ... IF $row['last_login'] Date() is the most current then grab that entry and count as 1. End result for user_id = 001 would be 1 entry count and not 10 (which I am getting now).
if ($results = $dbh->runQuery($sql)) {
foreach ($results as $key=>$row){
$users[$row['user_id']][] = array('user_id'=>$row['user_id'],
'racid' => $row['racid'],
'email' => $row['email'],
'last_login' => $row['last_login'],
'fname' => $row['fname'],
'lname' => $row['lname'],
'role_id' => $row['role_id'],
'role_name' => $row['role_name'],
'ios_device_token' => $row['ios'],
'roid_device_token' => $row['roid'],
'p_name' => $row['p_name']);
if($row['ios'] !== null && $row['ios'] !== '' && $row['ios'] !== '-1'){
$ios_count++;
}
if($row['android'] !== null && $row['android'] !== '' && $row['android'] !== '-1'){
$android_count++;
}
$invalidValues = [null, "", -1];
if(in_array($row['ios'], $invalidValues) && in_array($row['android'], $invalidValues)){
$desktop_count++;
}
}
}

Answer 1

Using associative arrays, you can "distinctify" by your own criterium. Something like the following code.
However what #esqew said (commenting your question) about altering the SQL instead of the PHP is probably a cleaner angle, especially since PHP is generally quite slow.
if ($results = $dbh->runQuery($sql)) { // that exists already
$latestEntries = []; // assoc. array: key=user, value=row
foreach ($results as $row) { // that exists already
// assuming 'last_login' is a timestamp or any format that can be used in inequality
// otherwise cook your own comparison function
if (
!$latestEntries[$row['user_id']]
|| $latestEntries[$row['user_id']]['last_login'] < $row['user_id']['last_login']
) {
$latestEntries[$row['user_id']] = $row;
}
// rest of your code that exists already
}
// here, after the loop, $latestEntries has the latest entry for each user found in $results
}