PHP method to query and delete duplicate data in multiple columns of database (implemented using array functions), multi-column array_PHP tutorial

How to query and delete duplicate data in multiple columns of the database with PHP (implemented using array functions), multi-column array

This article describes how to query and delete duplicate data in multiple columns of the database with PHP method. Share it with everyone for your reference, the details are as follows:

<&#63;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);
&#63;>

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