Running the same query multiple times - php

Question

I have been tasked to regenerate every class code, but there are over 4,000 and I'd rather not do that manually. I decided to make a test database with the same structure just to mess with it before I actually began messing with the live server.
I am having an issue trying to run the same query multiple times. I'd like to run it multiple times because I have a randomly generated string (that is also being generated every time this runs) that needs to replace other strings.
Any help, guys?
for ($i = 0; $i < 8; $i++) {
$password = str_rand();
$sql = "UPDATE test "
. "SET classCode = '$password'".
. "WHERE id = '$i'";
}
mysql_select_db('workshe3_worksheetwonder');
$retval = mysql_query( $sql, $conn );
if(! $retval ) {
die('Could not update data: ' . mysql_error());
}
echo "All codes regenerated successfully.";
mysql_close($conn);
}

Answer 1

Your code should look like this
mysql_select_db('workshe3_worksheetwonder');
for ($i = 0; $i < 8; $i++) {
$password = str_rand();
$sql = "
UPDATE test
SET classCode = '$password'
WHERE id = '$i'";
$retval = mysql_query($sql, $conn) or die('Could not update data: ' . mysql_error());
}
echo "All codes regenerated successfully.";
mysql_query() is the function that needs to go in the loop, as it's the thing that's actually doing the updating. Your $sql is just a string with the command in it. If you don't run the mysql_query() in your loop then your string just gets overwritten without being used.
mysql_ functions are deprecated, meaning you shouldn't really use them for new code. There are some examples of alternative protocols if you follow that link.