<?php $dsn = "mysql:host=localhost;dbname=group"; $db = new PDO($dsn, 'root', ''); $db->exec('set names utf8'); $sql = "select conf_id from  `group` group by conf_id"; //$pre = $db->prepare($sql); //$result_arr = array(); $pre = $db->query($sql); $result_arr = $pre->fetchAll(PDO::FETCH_ASSOC); //print_r ($result_arr); foreach ($result_arr as $v) {  echo $v[conf_id]."<br>";  $vv = $v[conf_id];  $re = array();  $sql1 = "select * from `group` where conf_id = '$v[conf_id]' order by time";  $sql2 = "select * from `group` where conf_id = '$v[conf_id]' order by time DESC";  $rs1 = $db->query($sql1);  $rs2 = $db->query($sql2);  $re1[$vv] = $rs1->fetchAll(PDO::FETCH_ASSOC);  $re2[$vv] = $rs2->fetchAll(PDO::FETCH_ASSOC);  print_r($re1[$vv][0]);  print_r($re2[$vv][0]); }