Get Mysql insert_id in java

If you are sending something back in an ajax request, you don't "return" it. That returns something back to your PHP script and NOT your browser. You output/echo something back to the browser.

Instead of

Code:

return $data;

Try

Code:

echo json_encode($data);

Then in your javascript success event:

Code:

function(data){
     //alert('success');  
     console.log(data);
});

Then check the js console of you browser. You should see a json object which contains 'post_id' and its value.