Comparing two NULL-able variables in T-SQL

Question

Let's say I have two variables which may be NULL, and I want to check if they are different.

But, I want to:

• Treat two NULLs as equal (not as NULL).
• Treat NULL and non-NULL as unequal (not as NULL).

I know I could just write:

DECLARE @v1 int = ...;
DECLARE @v2 int = ...;

IF (
    (@v1 IS NULL AND @v2 IS NOT NULL)
    OR (@v1 IS NOT NULL AND @v2 IS NULL)
    OR @v1 <> @v2
)
    PRINT 'Different!';

But is there a more elegant way?

Answer 1

Just to show there are many ways to do it.

IF EXISTS(SELECT @v1 EXCEPT SELECT @v2)
    PRINT 'Different'

Answer 2

There is one more option but I'm not sure whether it'll be more elegant.

IF NOT(NULLIF(@v1, @v2) IS NULL AND NULLIF(@v2, @v1) IS NULL)
PRINT 'Different!';