Magento

I’ve had several issues solved by “reindexing data”.  Is there a way to have it automatically do that every so often?

Issues:
- sales will expire, but some instances of the product don’t reflect
- category item order will be messed up

Thank you for your help!

I also want to know how to make it automatical.

You can search the code from backend for re-indexing.
And based on the code you can make cron job module for magento. Here goes the tutorial for this:
http://www.magentocommerce.com/wiki/1_-_installation_and_configuration/how_to_setup_a_cron_job

You can solve this problem using asynchronus queue. Check this one Fast Asynchronous Re-indexing http://mirasvit.com/magento-extensions/magento-asynchronous-reindex.html. After each product/category save this extension move reindex task to queue and process this queue as background process in cron.