algorithm howto,

[Manat]

Hi,
I have an online contest to do. With this contest,
there are 700 potential prize winners. Every entrant has
his own contestandtID, and how the contestantID works is
that a int is stored in a table, and when a user enters
his info, it takes this int and assigns that number as
his contestantID, and after it's assigned the int is
incremented by one for the next entrant.

In order for any of the entrants to win, pre-defined
contestandID winning numbers will be assigned. I need to
know how to do a script wherein a pattern is followed. I
wanted every 10th contestantID to be a winner, but now
i'm being asked to have both even and odd numbers, so I now need to allow for both even numbers and odd numbers.
Another issue is that the case is not that I have a database at the end of the contest full of entries, as soon as an entrant tries to enter, he gets instant notification whether he is a winner or not. So this adds a layer of complexity, as well as the winnings alternate and I need to know who won what.

I would apreciate any help on this, what would be the
best way to do this? And the winnings are
alternating, first winner gets prizeA, next winner gets prizeB, next winner gets prizeA, next winner gets prizeB and so on and so forth.

Am I right in assuming that winners cannot be radomized, due to it's prize alternating factor and that we have to stay within 700 winners without knowning how much traffic or entries we will get.

What would be the best way to tackle this?
Thanks
MK

[Manat]

Hello,

Can I just assign the prize randomly as you create a row for each
contestant. RAND() isn't very random but it should be good enough to give whatever percentage of winners needed, right?

CREATE TABLE Contestants (contestantid INTEGER PRIMARY KEY, prize CHAR(4)
NOT NULL)

INSERT INTO Contestants
SELECT COALESCE(MAX(contestantid),0)+1,
CASE WHEN CAST(RAND()10 AS INTEGER) % 6 = 0 THEN 'A'
WHEN CAST(RAND()10 AS INTEGER) % 3 = 0 THEN 'B'
ELSE 'NONE'
END
FROM Contestants