sql select in select query - sql

Question

I'm using plsql developer with oracle db
and i'm trying to select from some selection.
select *
from (select max(mrs.no), mrs.material_id
from material_route_step mrs, documents d
where d.document_id(+) = mrs.document_id
and mrs.prod_order_id = 121673
and d.document_type_id = 1
and mrs.unit_id = 2606
group by mrs.material_id) as sa,
material_route_step mrs1,
documents d1
where mrs1.material_id = sa.material_id
and mrs1.no = sa.no
and d.name like '%N%'
But i think my syntax isn't right. Thanks in advance.

Answer 1

It looks like your "d.name" reference might be incorrect as the "d" alias is on your Inner query vs d1 in your OUTER query... Maybe that should be a "d1.name", but you should also include your left-outer join (+) reference by the document ID too otherwise you will have a Cartesian result.
where
mrs1.material_id = sa.material_id
and mrs1.no = sa.no
and d1.document_id(+) = mrs1.document_id
and d1.name like '%N%'
But, to better offer an answer, I will try to answer by writing what I THINK you are looking for, then a query to get that. Since you are looking for the maximum "mrs.no", this would imply you want a JOIN and not a left-join via Oracle's syntax of (+)=, but for a specific product, document type and unit. Once that has been found, get every document name associated with the materials route.
select
*
from
( select
mrs.material_id,
max( mrs.no ) as maxno
from
material_route_step mrs
JOIN documents d
on mrs.document_id = d.document_id
AND d.document_type_id = 1
where
mrs.prod_order_id = 121673
and mrs.unit_id = 2606
group by
mrs.material_id ) PreQuery
JOIN material_route_step mrs2
on PreQuery.material_id = mrs2.material_id
AND PreQuery.maxno = mrs2.no
JOIN documents d2
on mrs2.document_id = d2.document_id
Without applying a join condition on your outer documents "d1" alias, you WILL get a Cartesian result set.