Hi Ben,
could you define what "first color in the color-table" means to you?
Table entries don't have a natural order. You have to specify that (e.g. via ORDER BY).
And If I understand you're requirement correctly, you want to have some kind of round-robin or random iterator of colors, right?
Otherwise, that is, if there is a mapping possible between the user data and the possible colors, you could just join the color information in the UPDATE statement, just as Henrique Pinto described it.
That's way faster then any looping/cursor calling will be.
- Lars