Php/MySQL help - random daily pick? - php

Question

I'm trying to get a pick from my DB that would last for a day (daily pick). I use the following code:
$query = 'SELECT * FROM table ORDER BY rand() LIMIT 1
But as you can see it only gives me a random pick from the table, and every time I refresh the page it gets me a new random pick. How can I make the pick to last for a whole day?
Thanks in advance <3
I'm trying this:
$query = "SELECT * FROM table ORDER BY rand(" . date("Ymd") . ") LIMIT 1";
But I get the following error: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource. This is the part that gets broken:
$results = mysql_query($query);
while($line = mysql_fetch_assoc($results))
So... it should look like this, right? (I mean, choosing the daily random pick?)
$dailyPick = 'SELECT * FROM table ORDER BY rand() LIMIT 1';
$cacheKey = 'dailyPick'. date('dmY');
if($cache->has($cacheKey)) {
$dailyPick = $cache->get($cacheKey);
} else {
// hit database
$dailyPick = $cache->save($cacheKey);
}
I'm trying this now:
$dailyPick = 'SELECT * FROM table ORDER BY rand() LIMIT 1';
$cacheKey = 'dailyPick'. date('dmY');
if($cache->has($cacheKey)) {
$dailyPick = $cache->get($cacheKey);
} else {
// hit database
$dailyPick = $cache->save($cacheKey);
}
However, it gets me a mistake that I'm using the 'has' function on a non-object.

Answer 1

If you set the SEED for the rand to an integer value that changes daily, that would solve your problem
$query = "SELECT * FROM table ORDER BY rand(" . date("Ymd") . ") LIMIT 1";
Would do the trick.

Answer 2

A sane means of doing this would be to automatically generate the pick of the day content via a cron job that was setup to run once a day.
As such, the cron job would execute the SQL you provided and store the appropriate content in a flat file/database table, etc. (or perhaps even just store the choosen id in another table for future lookup purposes).

Answer 3

You can try something like this:
$total = 'SELECT COUNT(*) FROM table;';
$query = 'SELECT * FROM table ORDER BY id ASC LIMIT 1 OFFSET ' . (date('Ymd') % $total) . ';';

Answer 4

I think you'll need to update the random picked record with "today" field = 1..
Something like this:
// ------------
// Run this 3 commands once a day
// Reset all records
mysql_query("UPDATE `table` SET `today` = 0");
// Pick one
$sql = mysql_query("SELECT `id` FROM `table` ORDER BY RAND() LIMIT 1");
$id = mysql_result($sql, 0, 'id');
// Update the record
mysql_query("UPDATE `table` SET `today` = 1 WHERE `id` = {$id}");
// ------------
// Now you can find again your "random found record":
$query = mysql_query("SELECT * FROM `table` WHERE `today` = 1");