Question

Okay… I’m lost (again). How can I make a custom seed for rand() that will keep the pick from the database for a specific period of time: 10 minutes, 1 hours, 1 day, etc.

I use this:

$query = 'SELECT * FROM table order by rand () LIMIT 1';

To get a random pick every time I refresh the page. I’ve been reading for days, but I just can’t find an example that explains how to make a custom seed that will keep the selection for a specific period of time. Please help me… sighs

Answer 1

As Dominic Rodger said – order by rand is horrible.
But I find using cron too big a gun for the job. (especially that You don’t know how)

You should rather generate a random integer number in php and store it and pass it to the mysql to something like that:

SELECT * FROM table WHERE id=(MOD('.$php_generated_random.', LAST_INSERT_ID())+1)

it gets a big random number and does modulo, so that it doesnt go over the table length.

This has a problem with LAST_INSERT_ID() though. Your mysql may return 0 there in many cases.

So the good’n’safe way to do that would be:

1. check if it’s time to generate new random
2. if so, then get the max id from table (assuming that table length changes sometimes)
3. generate a random number to be an id
4. store the id and generation time

and do only select where id=$sth