Hi Fabiom,

PMFJI

from my knowledge it is better to do

SELECT genus, species, continent ;
    FROM  Site S;
    INNER JOIN Species ON S.fkey =Species.Pkey AND S.continent IN ('Africa','Asia');
    INNER JOIN Site X ON X.fkey =Species.Pkey AND X.continent IN ('Africa','Asia') AND X.continent#S.continent ;
ORDER BY 1,2

Agnes
Update:
I mean

SELECT genus, species, continent ;
    FROM  Site S;
    INNER JOIN Species ON S.fkey =Species.Pkey AND S.continent IN ('Africa','Asia');
    INNER JOIN Site X ON X.fkey =Species.Pkey AND X.continent IN ('Africa','Asia') 
where X.continent#S.continent ;
ORDER BY 1,2

>Hi Ken,
>
>try this:
>

>SELECT genus, species, continent ;
>    FROM Species ;
>    INNER JOIN Site S ON S.fkey =Species.Pkey AND S.continent IN ('Africa','Asia');
>    INNER JOIN Site X ON X.fkey =Species.Pkey AND X.continent IN ('Africa','Asia') AND X.continent#S.continent ;
>ORDER BY 1,2
>

>
>Fabio