SQL WHERE statement?

Question

What should my WHERE clause be in a SQL Statement in which I want to return those rows where column A is null or column B is null, but not where both are null?

Answer 1

WHERE (ColA is NULL AND ColB is NOT NULL)
OR (ColB is NULL AND ColA is NOT NULL)

Answer 2

(A IS NULL OR B IS NULL) AND NOT (A IS NULL AND B IS NULL)