Question

Possible Duplicate:
IS NULL vs = NULL in where clause + SQL Server

Consider the following code – can someone explain to me why the one query doesn’t throw an error? I can understand why it doesn’t return a record, but what is it trying to do? Remember that colA is an int. It works the same on 2000,2005 and 2008 r2

create table #foo
( colA int )


insert into #foo
(colA)
values
(null)

select * from #foo --returns the one record we just created

select * from #foo where colA = null --does not throw an error and does not return a record! why??
select * from #foo where colA is null --returns the record

drop table #foo

Is there ever record that could exist in this table that would return for colA = null?

I dont have any other databases available to me at the moment to try this out – is this standard or is it behavior specific to MSSQL?

Answer 1

That is because a NULL can’t be equated to any value.

Disable the ANSI_NULLS option and then run it you will see the row now:

SET ANSI_NULLS OFF
select * from #foo --returns the one record we just created  
select * from #foo where colA = null --does not throw an error and does not return a record! why?? 
select * from #foo where colA is null --returns the record  drop table #foo