Updating a database value when you don't have the current value

Question

I need to write a query that updates the amount of points a
user has, even though i don't know how many they have currently.
This is part of a referal program. When a user gets another user to
join, the original user gets 15 more points. The problem is I do
not want to write a query that finds how many points the original
user has because that seems wasteful. It should look something
like..
<cfquery datasource="users" name="givepoints">
Update users
set points = [whatever the current value is + 15]
where userlogin = form.referer
</cfquery>
That line that has the value in the brackets is where i am
confused. I don't know the current value so how can i add 15 to
it?

Answer 1

In some databases, oracle for example, the use of
cfqueryparam speeds up your queries. It also has the potential to
simplify your code in that it handles things like apostrophes, so
you don't have to.
On the other hand, if you want to cache your query, you can't
use cfqueryparam. Also, if you are using some sort of logic to
build an sql variable to use in your query, it takes a lot of
effort (more than I'm prepared to give) to use cfqueryparam.
Also, not every db supports it.
cfqueryparam has it's place, but that place is not
everywhere.