[SQL] Problems with complex queries ...

Hey everybody !!! I am new on this list !!! I have a little problem . I try this on my system: (Postgres 6.5.2, Linux) "select n_lote from pedidos except select rp.n_lote from relpedidos rp, relfacturas rf where rp.n_lote=rf.n_lote group by rp.n_lote having sum(rp.cantidad)=sum(rf.cantida

[SQL] Complex query

Hey everybody !!! I am new on this list !!! I have a little problem . I try this on my system: "select n_lote from pedidos except select rp.n_lote from relpedidos rp, relfacturas rf where rp.n_lote=rf.n_lote group by rp.n_lote having sum(rp.cantidad)=sum(rf.cantidad)" I get this result: