Say if i had a mysql table called 'items', with fields 'ID', 'item_name' and 'rarity' how could i pick a random item thats rarity is lower than 80?

PHP Code:

$result = mysql_query("SELECT * FROM items WHERE rarity < 80 ORDER BY RAND() LIMIT 1");
$item = mysql_result($result,0,'item_name'); 


another thing, say if i had a table called users and fields called ID, name and tickets

how would i add up the total number of tickets then find a random number and echo that username, so if a person has more tickets they are more likely to be choosen?

For that I'd use a very similar approach to the one for picking your shop items randomly based on how rare they are. Add up the total tickets:

SELECT SUM(tickets) FROM users

Read out the users into an array, then in php generate a random number and add to it each users ticket number. When you exceed that ticket number, use that user. It's exactly the same as the shop code from your other thread except you don't invert the ticket number (more tickets is more likely whereas LESS rarity is more likely).

With your first example i get:

Warning: mysql_result(): Unable to jump to row 0 on MySQL result index 12 in /home/hsphere/local/home/cordy/simupets.com/random_item1.php on line 62