>>Probably I don't understand the type of query you are doing. If you have all the values hardcoded then go with that.
>
>Here is an example:
>
>

>SELECT Thread.Numero
> FROM Thread
> WHERE Thread.NoStatus=1 AND (Thread.NoClient=1 OR Thread.NoClient=2)
>

>
>That specific one can benefit of a compound index on NoStatus+NoClient.
>
>

>SELECT Thread.Numero
> FROM Thread
> WHERE Thread.NoStatus=1 AND
>  EXISTS (SELECT ForumCli.Numero FROM ForumCli WHERE ForumCli.NoMember=1 AND (ForumCli.NoClient=1 OR ForumCli.NoClient=2))
>

>
>That specific one uses the EXISTS to see if the child table has records.

Normally EXISTS is used in situations where you need to correlate one table with another. In your case where is no correlation, so the above is better written as

if exists(select 1 from ForumCli where NoMember = 1 and NoClient IN (1,2))

   select Numero from Thread where NoStatus = 1

else

    select Numero from Thread where 1=0 -- to produce empty result