unusual sql server query result

Question

Let's say I have a table called nameAge:

ID  Name  Age
1   X     12
2   Y     12
3   null  null
4   Z     12

and when I run a query like:

select * from nameAge where Age <> 12

it returns me an empty result set while I have row with id 3 where age is different than null?

Using Sql Server 2008 R2.

Any ideas?

Edit: Possibility to be duplicate with suggested answer may be at one point but does not cover at all and it shows how to use null values when compared with null but what I wanted to ask was about the result set which includes null values

Answer 1

This is the intended behavior. You cannot compare NULL values using = or <>. You have to use IS NULL or IS NOT NULL.

If you want NULL values only use IS NULL:

select * from nameAge where age IS NULL

If you want NULL values with age <> 12 values, use:

select * from nameAge where age <> 12 OR age IS NULL