Alright, let's say my MySQL table is set up with entries similar to:
id code sold
1 JKDA983J1KZMN49 0
2 JZMA093KANZB481 1
3 KZLMMA98309Z874 0
I'd like it to pick a random ID within the ranges already in the database (or just go from 1-X) and then just assign it to a variable for my own action to be taken. So let's say we want to pick a code that isn't sold (marked as 0 and not 1), then we'd pick it.
Now, it doesn't have to be 100% random, it could check if the first one is sold, if not, keep going. But I'm not 100% sure on how to go by this. Snippets would be appreciated because I can work out things easily on my own, I just need an example to see where I am going.
How about using a WHERE and ORDER BY RAND()
SELECT id, code
FROM tablename
WHERE sold = 0
ORDER BY RAND()
LIMIT 1
Have you tried
SELECT * FROM myTable WHERE sold = 0 ORDER BY RAND() LIMIT 1
Adding ORDER BY RAND() to the rest of your SELECT query is the most straightforward way to accomplish this.
If you don't need the random, then don't use it. It can affect performance very negatively. Since you mentioned in your post that it wasn't necessary, I would recomment using Ezequiel's answer above and dropping the rand. See Most Efficient Way To Retrieve MYSQL data in random order PHP for more info.
It seems that your codes are already random, so why not just take the first item; if you have many unsold records in your database, doing the typical ORDER BY RAND() will hurt the database performance.
SELECT *
FROM codes
WHERE sold = 0
LIMIT 1
FOR UPDATE;
I've also added FOR UPDATE to avoid race conditions, assuming that you're using transactions, as you update the record later (to actually sell it).