>>>>>Here is a sample:
>>>>>
>>>>>

>>>>>declare @t table (id int identity, col1 Int, col2 Int)
>>>>>
>>>>>insert into @t (col1, col2) values (1, 3), (2, 5)
>>>>>
>>>>>select * from @t where not (col1 > 3 and col2 < 6)
>>>>>
>>>>>select * from @t T where not exists (select * from @t T1 where col1 > 3 and col2 < 6 and T.id = T1.id)
>>>>>
>>>>>select * from @t where col1 <=3 or col2 >=6

>>>>>
>>>>>Normally NOT (condition1 and condition2) translates into opposite condition1 OR opposite condition2
>>>>
>>>>Yes, after second verification, I see that the execution is the same.
>>>>
>>>>I always use the NOT in such approach as it is more easy to understand. When I have something like this:
>>>>
>>>>

>>>>DECLARE @ModDate DateTime
>>>>DECLARE @NoStatus Int
>>>>DECLARE @ModDate2 DateTime
>>>>DECLARE @NoStatus2 Int
>>>>DECLARE @ModDate3 DateTime
>>>>DECLARE @NoStatus3 Int
>>>>
>>>>SET @ModDate='2013-11-09 10:31:18'
>>>>SET @NoStatus=5
>>>>SET @ModDate2='2014-11-03 10:31:18'
>>>>SET @NoStatus2=8
>>>>SET @ModDate3='2014-11-03 10:31:18'
>>>>SET @NoStatus3=7
>>>>
>>>>SELECT Client.Numero FROM Client (NOLOCK)
>>>> WHERE NOT (Client.ModDate<@ModDate AND Client.NoStatus=@NoStatus) AND
>>>>  NOT (Client.ModDate<@ModDate2 AND Client.NoStatus=@NoStatus2) AND
>>>>  NOT (Client.ModDate<@ModDate3 AND Client.NoStatus=@NoStatus3)
>>>>

>>>>
>>>>...it seems more easy to understand that the second one:
>>>>
>>>>

>>>>DECLARE @ModDate DateTime
>>>>DECLARE @NoStatus Int
>>>>DECLARE @ModDate2 DateTime
>>>>DECLARE @NoStatus2 Int
>>>>DECLARE @ModDate3 DateTime
>>>>DECLARE @NoStatus3 Int
>>>>
>>>>SET @ModDate='2013-11-09 10:31:18'
>>>>SET @NoStatus=5
>>>>SET @ModDate2='2014-11-03 10:31:18'
>>>>SET @NoStatus2=8
>>>>SET @ModDate3='2014-11-03 10:31:18'
>>>>SET @NoStatus3=7
>>>>
>>>>SELECT Client.Numero FROM Client (NOLOCK)
>>>> WHERE (Client.ModDate>=@ModDate OR Client.NoStatus<>@NoStatus) AND
>>>>  (Client.ModDate>=@ModDate2 OR Client.NoStatus<>@NoStatus2) AND
>>>>  (Client.ModDate>=@ModDate3 OR Client.NoStatus<>@NoStatus3)
>>>>

>>>
>>>This thing is still very hard to understand for me. I think the easiest here would be
>>>
>>>and Client.ModDate >=@MinDateOf3Dates OR Client.NoStatus NOT IN (@Status1, @Status2, @Status3)
>>
>>are you certain that all possible resultsets will be identical with your clause?
>
>Hard to say, but this one I can understand. The above 2 variations are too complex for me.

LMAO...