I had a page where the SQL data itself was being scraped from another page that was in a state of flux, and it would be important to viewers to know how current my page was in relation to the other page changes.
In my scraping script I simply included the line
touch myPage.php
so whenever the data was updated, the PHP page was as well; and on myPage.php used
<?php
echo " Last updated " . date ("F d Y H:i:s.", getlastmod());
?>
to show the time of last update. Hope this helps.