textarea content created by ajax not inserted into database

i have a piece of code written in php

i use ajax to display a textarea when a certain button is clicked. it works fine and it's being displayed.

next to the textarea there is a submit button created also by the same button-click, which should insert the textarea content into a database table once it's set. but that doesn't seem to work

any help? thanks

there is the ajax code:

function answer(post)
{
var xmlhttp = null;
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("answer").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","answer.php?p="+post,true);
xmlhttp.send();
}

and this is answer.php:

<?php
$p=$_GET['p'];

if (isset($_POST['_submit']) && $_POST['_text']!="") {
    $answer=$_POST['_text'];
    include 'db_connect.php';
    mysql_query("INSERT INTO answer (p, answer) VALUES ('$p', '$answer')");
    mysql_close($con);
}
else {
    echo '<form method="post">';
    echo '<texta开发者_如何转开发rea name="_text"></textarea>';
    echo '<input type="submit" name="_submit" value="post"/><';
    echo '</form>';
}
?>

Did you try setting the action attribute to the form?