Nested SQL Queries

Question

Hi,
I have a question for hierarchical queries.Suppose we have three tables manufacturer,brand and product.I wish to generate the XML for this query.The query I gave is as follows
select a.manid ,b.brandid,c.prodid
from manufacturer a
,brand b
,product c
where b.manid=a.manid
and c.prodid=b.productid
With this query the xml tags for brand and product appears many many times.We wish the reuslt in the following way.
<MANUFATURER>
<NAME> M1</NAME >
<BRAND>
<NAME>B1</NAME>
<PRODUCT>
<NAME>P1</NAME>
</PRODUCT>
<PRODUCT>
<NAME>P2</NAME>
</PRODUCT>
</BRAND>
<BRAND>
<NAME>B2</NAME>
<PRODUCT>
<NAME>P1</NAME>
</PRODUCT>
<PRODUCT>
<NAME>P2</NAME>
</PRODUCT>
</BRAND>
</MANUFACTURER>
I have used cast and multiset but it doesnt give the the result which we want.
When I am executing the following query it gives error inconsistent datatypes.
select manid,cast(multiset(select brandid,cast(multiset(select prodid from product
where product.prodid=brand.productid
)as p1_list)product
from brand
where brand.manid=manufacturer.manid)as b1_list)brand
from manufacturer
How can I write the query using the cast and multiset ?Is there any other way?I
Have seen with two tables cast and multiset works fine.
Please help me.
Thanks.
Pooja
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Answer 1

The objects feature currently available does not support multiple levels of nesting with
respect to collections (it supports multiple levels of nesting of object types).
To overcome this, you need can use the CURSOR() subquery. The CURSOR() is a way of evaluating subqueries in the SELECT List.
e.g.
select manid, CURSOR(
select brandid,
CURSOR(select productid from
from product p
where p.brandid = b.brandid)
AS productlist
from brand b
where b.manid = m.manid) AS brandlist
from manufacturer m
will produce u a result like,
<ROWSET>
<MANID>100</MANID>
<BRANDLIST>
<BRANDLIST_ROW>
<BRANDID>200</BRANDID>
<PRODUCTLIST>
<PRODUCTLIST_ROW>
<PRODUCTID>2000</PRODUCTID>
</PRODUCTLIST_ROW>
.... // more productlist_rows
</PRODUCTLIST>
</BRANDLIST_ROW>
... // more brandlist rows
</BRANDLIST>
... more rows..
</ROWSET>
Hope this helps,
Murali
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