how to delete specific index with comparing - php

Question

i want to delete some index with comparing but it is not easy
first one our php version is 5
for example my result is like this
it is echo by json_encode and it was array
and the data is dynamic
[
{
"idx": "1",
"mom_member_idx": "1",
"teacher_member_idx": "2",
"care_start_datetime": "2019-09-09 08:30:00",
},
{
"idx": "2",
"mom_member_idx": "1",
"teacher_member_idx": "2",
"care_start_datetime": "2019-09-10 08:30:00",
},
{
"idx": "3",
"mom_member_idx": "2",
"teacher_member_idx": "2",
"care_start_datetime": "2019-09-09 08:30:00",
}
]
and i want to result like this comparing and unset with the latest one
[
{
"idx": "1",
"mom_member_idx": "1",
"teacher_member_idx": "2",
"care_start_datetime": "2019-09-09 08:30:00",
},
{
"idx": "3",
"mom_member_idx": "2",
"teacher_member_idx": "2",
"care_start_datetime": "2019-09-09 08:30:00",
}
]
i tried like this but it is not work
while ($r = mysqli_fetch_assoc($chat_list)) {
$dbdata[] = $r;
}
for($r=0;$r<sizeof($dbdata);$r++){
if ($dbdata[$r]['mom_member_idx']+$dbdata[$r]['teacher_member_idx']==$dbdata[$r+1]['mom_member_idx']+$dbdata[$r+1]['teacher_member_idx'])
{
if($dbdata[$r]['care_start_datetime']<$dbdata[$r+1]['care_start_datetime']){
unset($dbdata[$r]);
}else {
unset($dbdata[$r+1]);
}
}
}

Answer 1

First, convert your JSON array into a PHP array. then you can remove the array elements using the array index
$someArray = json_decode($someJSON, true);

Answer 2

You can sort the data by descending order by care_start_datetime using usort() and unset the first index form that sorted data.
Code example:
$data = json_decode('[
{"idx": "1","mom_member_idx": "1","teacher_member_idx": "2","care_start_datetime": "2019-09-09 08:30:00"},
{"idx": "2","mom_member_idx": "1","teacher_member_idx": "2","care_start_datetime": "2019-09-10 08:30:00"},
{"idx": "3","mom_member_idx": "2","teacher_member_idx": "2","care_start_datetime": "2019-09-09 08:30:00"}
]', true);
usort($data, function($a, $b) {
return strtotime($a['care_start_datetime']) > strtotime($b['care_start_datetime']) ? -1 : 1;
});
unset($data[0]);
print_r($data);
Working demo.

Answer 3

Your variant with summing to columns is not totally correct, because sum of some integers give you wrong result and you can accidentally remove the wrong one. Like 2 + 3 == 1 + 4 not correct.
Maybe that code helps you:
$groupedData = array();
while ($r = mysqli_fetch_assoc($chat_list)) {
// We create unique key for group same rows
// (with the same 'mom_member_idx' and 'teacher_member_idx')
$uniqueKey = implode('_', [$r['mom_member_idx'], $r['teacher_member_idx']]);
if (!array_key_exists($uniqueKey, $groupedData)) {
$groupedData[$uniqueKey] = array();
}
// Add row to grouped array by our unique key
$groupedData[$uniqueKey][] = $row;
}
$result = array();
foreach ($groupedData as $rows) {
// If in grouped array with that unique key only one row - just add it
if (count($rows) <= 1) {
$result[] = $rows[0];
continue;
}
// Go for all same rows and check date
$neededRow = null;
foreach ($rows as $row) {
// Here I don't understand what kind of date do you want - minimum or maximum
// You just can reverse the sign
if (
is_null($neededRow) ||
strtotime($row['care_start_datetime']) > strtotime($neededRow['care_start_datetime'])
) {
$neededRow = $row
}
}
if ($neededRow) {
$result[] = $neededRow;
}
}

Answer 4

For delete specific index first you need to convert JSON array into PHP array using json_decode() function, once you convert it into PHP array you can remove specific index using key,
foreach ($data as $key => $element) {
$value = $element['...'];
if (...) {
unset($data[$key]);
// or
$data[$key]['...'] = '...';
}
}
Hope this helps you.