Nesting of MySQLi prepared statements - php

Question

I have two prepared statements (for example) where the second statement is to be executed within the while(stmt1->fetch()){} loop. But, the inner statement (stmt2) doesn't execute within the first while loop:
<?php
$mysqli = new mysqli("localhost","root","","test");
if(mysqli_connect_errno())
{
printf("connection failed: %s\n",mysqli_connect_error());
exit();
}
$stmt1 = $mysqli->prepare("select id from posts");
$stmt2 = $mysqli->prepare("select username from members where id=?");
$stmt1->execute();
$stmt1->bind_result($ID);
while($stmt1->fetch())
{
echo $ID.' ';
/*Inner query*/
$stmt2->bind_param('i',$id);
$id =$ID;
$stmt2->execute();
$stmt2->bind_result($username);
while($stmt2->fetch())
{
echo 'Username: '.$username;
}
/*Inner query ends*/
}
?>
If I cut-paste the inner query part outside the outer while loop, it executes,but it is useless. What should I do to execute it properly?

Answer 1

Why do nested loop on it, when you can do INNER JOIN instead.
<?php
$mysqli = new mysqli("localhost","root","","test");
if(mysqli_connect_errno())
{
printf("connection failed: %s\n",mysqli_connect_error());
exit();
}
if($stmt1 = $mysqli->prepare("SELECT posts.id,members.username FROM posts INNER JOIN members ON posts.id=members.id")){
$stmt1->execute();
$stmt1->bind_result($id,$username);
while($stmt1->fetch()){
printf("ID # %d.<br>Username: %s<br><br>",$id,$username);
}
$stmt1->close();
}
$mysqli->close();
?>