Binding results in MySQLi - php

Question

In the code below if I try to fetch results after two successive executions with different sets of parameters, it shows the same result set(the first one twice), instead of showing both the results with different parameters. What should I do? Also, in the PHP manual $sqli->bind_results() is put after $sqli->execute(), is it always mandatory or is it valid also to put $sqli->bind_results() before $sqli->execute() ?
<?php
$mysqli = new mysqli("localhost","root","","test");
/*check connection*/
if(mysqli_connect_errno())
{
printf("connection failed: %s\n",mysqli_connect_error());
exit();
}
/*create prapared statement*/
$sqli = $mysqli->prepare("select post_id from posts where id=?");
/*bind params*/
$sqli->bind_param('i',$id);
/*set params*/
$id =1;
/*execute prapared statement*/
$sqli->execute();
/*bind results*/
$sqli->bind_result($post_id);
while($sqli->fetch())
{
echo ' '.$post_id;
}
echo '<br/>fetch new record<br/>';
/*set params*/
$id =2;
/*execute prapared statement*/
$sqli->execute();
while($sqli->fetch())
{
echo ' '.$post_id;
}
Executing in loops:*
Scene1: calling bind_result($post_id) repeatedly
<?php
$mysqli = new mysqli("localhost","root","","test");
/*check connection*/
if(mysqli_connect_errno())
{
printf("connection failed: %s\n",mysqli_connect_error());
exit();
}
/*create prapared statement*/
$sqli = $mysqli->prepare("select post_id from posts where id=?");
/*bind params*/
$sqli->bind_param('i',$id);
for($x=0;$x<1000;$x++)
{
$id =$x;
$sqli->execute();
/*****bind results*****/
$sqli->bind_result($post_id);
while($sqli->fetch())
{
echo ' '.$post_id;
}
}
?>
Scene2: calling bind_result($post_id) once
<?php
$mysqli = new mysqli("localhost","root","","test");
/*check connection*/
if(mysqli_connect_errno())
{
printf("connection failed: %s\n",mysqli_connect_error());
exit();
}
/*create prapared statement*/
$sqli = $mysqli->prepare("select post_id from posts where id=?");
/*bind params*/
$sqli->bind_param('i',$id);
/*****bind results*****/
$sqli->bind_result($post_id);
for($x=0;$x<1000;$x++)
{
$id =$x;
$sqli->execute();
while($sqli->fetch())
{
echo ' '.$post_id;
}
}
?>
Now,as par PHP manual bind_result() should be used after execute(),but as shown in the scene1 above this will call "bind_result()" repeatedly whereas in scene2 it is called just once and still it is doing well. Which approach is better? Is scen2 valid?

Answer 1

Yes, you need to run bind_result after each execute.
From the manual...
Note that all columns must be bound after mysqli_stmt_execute() and prior to calling mysqli_stmt_fetch().
So, you're only missing the second (required) call to bind_result...
$id = 2;
$sqli->execute();
$sqli->bind_result($post_id);