PHP查询并删除数据库多列重复数据的方法(利用数组函数实现)

<?php$con = mysql_connect("localhost","root","");if (!$con){    die('Could not connect: ' . mysql_error());}$db_selected = mysql_select_db("test_db", $con);if (!$db_selected){    die ("Can/'t use test_db : " . mysql_error());}$sql = "SELECT * FROM friend";$result=mysql_query($sql,$con);while($myrow=mysql_fetch_row($result)){    $arr_data[$myrow[0]]=$myrow[1]."-".$myrow[2];}$arr_unique=array_unique($arr_data);$arr_rep=array_diff_assoc($arr_data,$arr_unique);//显示前后量echo count($arr_data)."-".count($arr_unique);foreach($arr_rep as $key=>$value){  $sql_del = "DELETE FROM friend WHERE id = '{$key}' ";  $result=mysql_query($sql_del,$con);}// 一些代码mysql_close($con);?>