Wie implementiert man eine Kommentarfunktion in PHP?

<form action="pinglunchili.php" method="post">
<textarea name="content"></textarea>
<div><input type="submit" value="评论" /></div>
 
</form>

<?php
 
$yonghu="caocao";
 
$content=$_POST["content"];
$time =  date("Y-m-d H:i:s");
 
 
require "DBDA.class.php";
$db=new DBDA();
$sql="insert into pinglun values(&#39;&#39;,&#39;{$yonghu}&#39;,&#39;{$content}&#39;,&#39;{$time}&#39;)";
 
if($db->query($sql,0))
{
    header("location:pinglun.php");
}
else
{
    echo "你输入错误！";
}

<?php
 
require "DBDA.class.php";
$db=new DBDA();
$sql="select * from pinglun";
$arr=$db->query($sql);
 
foreach($arr as $v)
{
     
    echo "<div>{$v[0]}</div>
          <div>{$v[1]}</div>
              <div>{$v[2]}</div>
          <div>{$v[3]}</div>
          <form action=&#39;huifuchuli.php?id={$v[0]}&#39; method=&#39;post&#39;>
          <input type=&#39;text&#39; name=&#39;Comment&#39; />
                  <input type=&#39;submit&#39; value=&#39;回复&#39; /></form>";
    $dc = new DBDA();    
    $sql1="select * from huifu where jieshouid={$v[0]}";
    $arr1=$dc->query($sql1);
    foreach($arr1 as $f)
    {
        echo "<div style=&#39;color:red&#39;>{$f[0]}</div>
              <div style=&#39;color:red&#39;>{$f[2]}</div>
              <div style=&#39;color:red&#39;>{$f[3]}</div>
              <div style=&#39;color:red&#39;>{$f[4]}</div>
             ";
    }
}
?>

<form action=&#39;shanchuchuli.php?id={$v[0]}&#39; method=&#39;post&#39;>
             <input type=&#39;submit&#39; value=&#39;删除&#39; /></form>
         <form action=&#39;huifuchuli.php?id={$v[0]}&#39; method=&#39;post&#39;>
         <input type=&#39;text&#39; name=&#39;Comment&#39; />
         <input type=&#39;submit&#39; value=&#39;回复&#39; /></form>";