SQL WHERE语句？

Question

我的WHERE子句应该在SQL语句中应该返回哪些行，其中列A为空或列B为空，而不是两者都为空？

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)