替换数组中最新的n个日期时间

Question

I'm trying to replace all datetime values in an array from a MYSQLi query that are not the oldest 2. I've tried getting the results with the query, but it seems too complex since I need to do this for multiple columns. Is there a way to do this with PHP?

So if:

$row["item"] =
"2014-01-01 00:00:00 2014-04-04 00:00:00 2014-02-02 00:00:00 2014-03-03 00:00:00"

Return:

$row["item"] = 
"2014-01-01 00:00:00 new 2014-02-02 00:00:00 new"

Update

My apologies, I may be mistaken... if my member's listings are created within a while loop, is an array even returned, or is one $row["item1"], $row["item2"], etc. returned with each pass? The challenge I'm facing is comparing datetimes between multiple rows (my members) for each column (item1 - item10).

The current counter limits the items to 12, but does not take into account the datetimes...

while ($row = mysqli_fetch_array($result)){

  if($row["item1"]!="0000-00-00 00:00:00"){ // if datetime is set
    $item1cnt++;                            // add one to counter
    if($item1cnt > 12){                     // if counter is greater than 12
      $row["item1"]="";                     // itemx = ""
    }else{                                  // if counter is less than 12
      $row["item1"]="item1";                // item = itemx
    }
  }else{                                    // if datetime is not set
      $row["item1"]="";                     // itemx = ""
   }

// repeat above for all 10 items


// part of member's listing used by jquery to filter services
$items[] = "<li class=\"services " . $row["item1"] . " " . $row["item2"] . " " . $row["item3"] . " " . $row["item4"] . " " . $row["item5"] . " " . $row["item6"] . " " . $row["item7"] . " " . $row["item8"] . " " . $row["item9"] . " " . $row["item10"] . "\">";

  }

//an example situation for listings...the first twelve list their services
<li class="services item1 item2 item3 item4       item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">
<li class="services item1 item2 item3 item4 item5 item6 item7 item8 item9 item10">

//then another lists for all 10 services(items) but only item5 is available. The
 current code accomplishes this.
<li class="services                         item5                               ">

However, if the first member decides to offer item5, it will push the new guy off. So I need to use datetime to establish rank.

Solution

My sql query now uses LEFT JOIN and LIMIT for each of the items. @DarkSide provided the solution here

Answer 1

I think you have good SQL query for what you are trying to accomplish in https://stackoverflow.com/a/24225215/350021

But here is the answer for your current question:

function transformItems($items, $preserve) {
    $items = array_map('rtrim', str_split($items, 20));
    asort($items);
    array_walk($items, function(&$val, $key, &$i) {
        if (--$i < 0) {
            $val = 'new';
        }
    }, $preserve);
    ksort($items);
    return implode(' ', $items);
}

// sample usage
$row["item"] = "2014-01-01 00:00:00 2014-04-04 00:00:00 2014-02-02 00:00:00 2014-03-03 00:00:00";
$row['item'] = transformItems($row['item'], 2);
// result: "2014-01-01 00:00:00 new 2014-02-02 00:00:00 new"