T-SQL: How to make a positive value turn into the equivalent negative value (e.g "10.00" to "-10.00"

Ok so i have a DECIMAL field called "Score". (e.g 10.00)

Now, in my SP, i want to increment/decrement the value of this field in update transactions.

So i might want to do this:

SET @NewScore = @CurrentScore + @Points

Where @Points is the value im going to increment/decrement.

Now lets say @Points = 10.00.

In a certain scenario, i want 10.00 to become -10.00

So the statement would be translated to:

SET @NewScore = @CurrentScore + -10开发者_运维技巧.00

How can i do that?

I know its a strange question, but basically i want that statement to be dynamic, in that i dont want to have a different statement for incrementing/decrementing the value.

I just want something like this:

SET @Points = 10.00
IF @ActivityBeingPerformedIsFoo
BEGIN
   -- SET @Points to be equivalent negative value, (e.g -10.00)
END
SET @NewScore = @CurrentScore + @Points

Can't you just multiply it by -1?

I always do 0 - @Points. It was this way in some code I inherited. "A foolish consistency..."

Multiply @Points by -1 in that certain scenario.

I thought of subtracting it with a multiple of 2, i.e. x - 2x