Celui-ci fonctionnera, mais est assez moche
select p.intProductId, p.strProductName, pi.strImageName
from tblProducts p
inner join tblProductImages pi on pi.intProductID = p.intProductId
inner JOIN (select min(intOrder) minOrder, intProductID
FROM tblProductImages
GROUP BY intProductID) s
on s.intProductID = p.intProductID and s.minOrder = pi.intOrder
union
select p.intProductId, p.strProductName, pi.strImageName
from tblProducts p
left join tblProductImages pi on pi.intProductID = p.intProductId
where pi.intProductID is null;
alternatif :
select p.intProductId, p.strProductName, pi.strImageName
from tblProducts p
left join tblProductImages pi on pi.intProductID = p.intProductId
where pi.intProductId is null or pi.IntOrder = (select min(intOrder)
from tblProductImages
where intProductId = pi.intProductId);
