Best way to work around NOT IN NULL issue

exceptnullstored-proceduressybase

There are plenty of explanations of why NOT IN NULL doesn't work, but I didn't see any solutions. (recent question here: Why does NOT IN with a set containing NULL always return FALSE/NULL?)

I have 6 optional arguments to a stored procedure that are used to filter a certain value of a query. The previous developer did something like this:

IF @var1 IS NULL AND ..... 

    select ...

else

    select ...
    where value in (@var1, ...)

I didn't particularly like this. (The query is quite massive), so I decided to opt for something like this:
(We had the results in a temp table anyway)

IF @var IS NOT NULL OR ...

    delete from #temp where value not in (@var1,...)

But I realized that this won't work.

The only thing I can think to do is to create another temp table that will hold only the not-null values in @var1, etc. (Either using if statements or deleting where is NULL) and then doing a join delete on this table.

Is there a better way?

Best Answer

Don't know about Sybase but in SQL Server you can do like this.

select *
from yourtable
where value not in (select N
                    from (values (@var1),
                                 (@var2),
                                 (@var3),
                                 (@var4),
                                 (@var5)) T(N)
                    where N is not null)

If you can't use values to create a derived table you can use union all instead.

where value not in (select N
                    from (select @var1 union all
                          select @var2 union all
                          select @var3 union all
                          select @var4 union all
                          select @var5) T(N)
                    where N is not null)
Related Question