Comparing nulls in Oracle SQL

Question

如果两个值相等，如果它们可以是除以下之外的空值，是否有更好的比较方法？

a = b or (a is null and b is null)

Answer 1

You can:

a=b or coalesce(a,b) is null

You could also use nvl , but that is a legacy function and coalesce is quicker, since it stops at the first non-null

Answer 2

You can use DECODE(A,B,1) = 1

DECODE is irregular in its treatment of NULLs.

However I think the intention is unclear and prefer vol7ron's answer. Clarity over minimising typing !

Answer 3

您可以使用nvl将其包装并将其设置为您的集合中不期望的某个值：

NVL(a,0) = NVL(b,0)