What is the result when comparing two nulls in SQL?

Posted Date: 19 Jul 2008	Resource Type: Articles	Category: Databases
Author: Gaurav Arora	Member Level: Diamond
Rating:	Points: 10

The answer is quite interesting with my stuff. Let me clear it in more writting:

1. When we compare two nulls then the result always 'false'. The main reason is the null is not a value its neither an empty nor a empty space, so the actual result is null which places as null.
2. When we compare a null with another which has some value like some int value then the result is false. The actual result is false and not null.

Consider the following examples:

--null = null is null which is false
Declare @intNull1 int
Set @intNull1 =null
Declare @intNull2 int
Set @intNull2=null
If @intNull1=@intNull2
Print 'null = null is true'
Else
Print 'null = null is false'

--Now assign some value
Set @intNull1 = 1
If @intNull1=@intNull2
Print 'null = int value is true'
Else
Print 'null = int value is false'

For more details, visit http://stuff4mdesktop.blogspot.com/2008/07/what-is-result-when-comparing-two-nulls.html

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