PHP method to query and delete duplicate data in multiple columns of database (implemented using array functions)_php skills

The example in this article describes how to query and delete duplicate data in multiple columns of the database using PHP. 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;>

Readers who are interested in more PHP-related content can check out the special topics of this site: "PHP Object-Oriented Programming Introductory Tutorial", "Summary of PHP String Usage ", "php mysql database operation introductory tutorial" and "php common database operation skills summary"

I hope this article will be helpful to everyone in PHP programming.