The trick is in this line: isnull(nullif(val1, val2), nullif(val2, val1)) is null

————————————–
————————————–
if object_id(‘tempdb..#test’) is not null drop table #test
create table #test (
val1 varchar(50),
val2 varchar(50)
)

insert into #test
select ‘Bill’, ‘Bill’
union all
select null, null
union all
select ‘Bill’, null
union all
select ‘Bill’, ‘Gates’
union all
select null, ‘Gates’

select
val1,
val2,
case
when val1 = val2 then ‘(wrong) equal’
else ”
end as WrongEquals,
case
when (val1 val2) then ‘(wrong) NOT equal’
else ”
end as WrongNotEquals,
NULLIF(val1, val2) as NullIf1_2,
NULLIF(val2, val1) as NullIf2_1,
case
when isnull(nullif(val1, val2), nullif(val2, val1)) is null then ‘eqivalent!’
else ”
end as OddlyCorrect_Equivalent,
case
when isnull(nullif(val1, val2), nullif(val2, val1)) is not null then ‘NOT eqivalent!’
else ”
end as OddlyCorrect_NotEquivalent
from
#test
————————————–
————————————–

Enjoy wrapping your mind around that.

ALTER PROCEDURE [dbo].[sp_datadump_selectfromcheckbox]
@project_ID int,
@Title_isChecked bit

AS
BEGIN
SELECT PRSDATA.Anomaly_ID,

CASE WHEN @Title_isChecked =’1′ THEN (Select PRSDATA.Title) END ‘ ‘

from PRSDATA,PRSDATA1, PRSDATA2, PRSDATA3, PRSDATA4, PRSDATA5, PRSDATA6, PRSDATA7 , PRSDATA8
WHERE PRSDATA.anomaly_id = PRSDATA1.anomaly_id and
PRSDATA.anomaly_id = PRSDATA2.anomaly_id and
PRSDATA.anomaly_id = PRSDATA3.anomaly_id and
PRSDATA.anomaly_id = PRSDATA4.anomaly_id and
PRSDATA.anomaly_id = PRSDATA5.anomaly_id and
PRSDATA.anomaly_id = PRSDATA6.anomaly_id and
PRSDATA.anomaly_id = PRSDATA7.anomaly_id and
PRSDATA.anomaly_id = PRSDATA8.anomaly_id and
PRSDATA.Main_Project_Affected = @project_ID

END
if (@@error = 0)
begin
RETURN 0
end
else
begin
RETURN 1
end

select Case IsNull(@Test, 2) —
when 2 Then ‘IS NULL’
else ‘NOT NULL’
End Result

That should do it.

declare @Test bit
set @Test = NULL
/*
Change to
set @Test = 0 or
set @Test = 1
keeping every other SET line remarked to check different
behaviours.
*/

select Case IsNull(@Test, 0) —
when 0 Then ‘IS NULL’
else ‘NOT NULL’
End Result

That will work just fine.

declare @Test bit;
set @Test = ‘false’;

select ( Case When IsNull(@Test, ”) = ”
Then ‘IS NULL’
Else ‘NOT NULL’
End);

I would expect ‘NOT NULL’ to be returned as @Test is set to a value ‘false’. However ‘IS NULL’ is output instead.

Does SQL Server treat NULL the same as ‘false’?

I was expecting it to be done without using WHILE but I did not make that clear in question so it works.
Good Work. I modified your code to show how the infinite code can be generated. However following script will run till 10 iteration and will stop.

SET ANSI_NULLS OFF

DECLARE @test AS INT
SET @test = 1

WHILE ISNULL( NULLIF(@test, @test), @test ) = @test
BEGIN
PRINT ‘HI’
SET @test = @test + 1
IF @test > 10
BREAK
END
GO

Warning : Do not run this code on production machine. Make sure you test it. The reason it is published here, so user who have similar problem can prevent infinite loop from happening.

DECLARE @test AS INT
SET @test = 1

WHILE ISNULL( NULLIF(@test, @test), @test ) = @test
BEGIN
PRINT ‘HI’
BREAK
END

Making @test = NULL would still make it print ‘HI’

Maybe this ?

IsNull(null, nullif(1, 1)), but I guess it would just return null :P