Using a condition in a while loop - php

Question

I have this code
$dbh = new PDO('mysql:host=localhost;dbname=odesk', 'root', '123456');
$sth = $dbh->prepare("SELECT id,msisdn from new_r4 limit 1,10");
$sth2 = $dbh->prepare("SELECT status from flag where id = 1");
$sth->execute();
$sth2->execute();
while ($result = $sth->fetch(PDO::FETCH_ASSOC)) {
$result2 = $sth2->fetch(PDO::FETCH_ASSOC);
$flag = $result2['status'];
$the_number = $result['msisdn'];
$id = $result['id'];
while ($flag == 0) {
echo 'Waiting.......' . PHP_EOL;
sleep(1);
}
//Part of the condition,just added
while ($flag == 1) {
echo $the_number . ' ' . $id .' ' . PHP_EOL;
sleep(1);
}
}
which is a a cli script that displays some numbers from my address book if a certain condition is met.If a the flag is 0 then no number shall be displayed and when the flag is 1,then display the number.
The problem is,i can't find the right condition to use after
while ($flag == 0) {
echo 'Waiting.......' . PHP_EOL;
sleep(1);
}
The if , else and case do not wait up until the flag is 1.
What condition can i use to get the script to display the numbers when $flag == 1?.

Answer 1

You're using $result2 and $result1. Your $flag will always be the value id = 1 because the WHERE clause never changes - so either $flag will always be either 1 or another value (from your question, it's going to always be another value). Either change your query to join the table, or query whilst in the while loop.
Assuming new_r4.id = flag.id
SELECT r.`id`, r.`msisdn`, f.`status`
FROM new_r4 r
LEFT JOIN flag f
ON r.id = f.id
LIMIT 1, 10
Change your code to become
while ($result = $sth->fetch(PDO::FETCH_ASSOC)) {
$flag = $result['status'];
$the_number = $result['msisdn'];
$id = $result['id'];
Now all you need to do is check $flag is equal to 1, and you're golden.
if($flag == 1) {
echo $this_number . PHP_EOL;
}

Answer 2

The while ($flag == 0) { is infinite and will never break out ($flag never changes within the loop); so the rest of the code is never executed.
Why not just use a simple if/else statement ?
if($flag===1){
echo $the_number . ' ' . $id .' ' . PHP_EOL;
}else{
echo 'Waiting.......' . PHP_EOL;
}