>Hi
>
>I'm extracting some records and I want to exclude some of them from being extracted.
>
>So I say
>

>SELECT * from member 
>where individual ref not in (select individual_ref from attribute where attribute.attr_code_ref = 1242 and individual_ref is not NULL and valid_to < getdate())
>

>Is that the best way of doing this. ?
>
>Thanks

You can find the best way if you turn Actual Execution plan on and test several different queries and check what is faster.
I prefer to write it with LEFT JOIN but this could be slower than yours, also the is NOT EXISTS() clause.
Check them all and choose faster :-).