>Try
>

>select Numero from Client where exists (select 1 from Invoice 
>where Invoice.Numero=Client.NoInvoice AND Invoice.SecondCondition=True)
>OR exists (select 1 from Inventory 
>where Inventory.Numero=Client.NoInventory AND Inventory.SecondCondition=True)

>
>This way either of the conditions will be true.

Yes, I believe this is what I posted in Message #1619009.

I, however, need to keep the LEFT JOIN as I need some fields in the result from those tables.