Selecting data Ajax - php

Question

I would like to select streamitem_id from my insert.php and add it to my existing post div. I'm needing the id of the post made so I can add it into my div so later when I add my delete button it will delete the post and the div that holds it. Hope I've made sense and I can do this with what I have as I'm trying to learn but it is a difficult language like any when first starting out.
AJAX
<script>
$(document).ready(function(){
$("form#myform").submit(function(event) {
event.preventDefault();
var content = $("#toid").val();
var newmsg = $("#newmsg").val();
$.ajax({
type: "POST",
url: "insert.php",
data: "toid=" + content + "&newmsg=" + newmsg,
success: function(){
$("#homestatusid").prepend("<div id='divider-"+WHERE MY STREAMITEM_ID NEEDS TO BE+"'><div class='userinfo'>"+newmsg+"</div></div>");
}
});
});
});
</script>
INSERT.PHP
$check = "SELECT streamitem_id FROM streamdata WHERE streamitem_id=$user1_id";
$check1 = mysql_query($check);
$check2 = mysql_num_rows($check1);
echo $check2;

Answer 1

In your javascript should be
$.ajax({
type: "POST",
url: "insert.php",
data: {toid:content, newmsg: newmsg}, # pay attention to this line
success: function(data){
$("#homestatusid").prepend("<div id='divider-"+data+"'><div class='userinfo'>"+newmsg+"</div></div>");
}
});
PHP
$toid = isset($_POST['toid']) ? $_POST['toid'] : null;
$newmsg = isset($_POST['newmsg']) ? $_POST['newmsg'] : null;
And do not use mysql_* since it deprecated

Answer 2

The first argument passed to the success callback is the responseText from the AJAX call. Modify your jQuery code to this:
success: function(responseText){
$("#homestatusid").prepend("<div id='divider-"+responseText+"'><div class='userinfo'>"+newmsg+"</div></div>");
// I'm assuming that insert.php returns just the ID you're interested in
}

Answer 3

success: function(response){
$("#homestatusid").prepend("<div id='divider-"+response+"'><div class='userinfo'>"+newmsg+"</div></div>");
}