- explode: documentation ( source)
<?php
$arr = explode("|", "ID1==Vasya==200==URL1|ID2==Petya==100==URL2|ID3==Sergey==300==URL3");
$min = PHP_INT_MAX;
$res = 0;
foreach($arr as $k){
$els = explode("=", $k);
if ($els[4] < $min){
$res = $els[4].",".$els[0].",".$els[2].",".$els[6];
$min = $els[4];
}
}
echo $res;