Looping thorugh nested tables in oracle and returning a list of objects to java

Question

I have this table created as follow:

    CREATE TABLE FORNECPRODS 
       (    SUPPLIER FORNEC_OBJ , 
        PRODUCTS PRODTABLE 
       )NESTED TABLE "PRODUCTS" STORE AS "PRODUCTSTABLE";
    /

    create or replace
    type PRODTABLE as table of PROD_OBJ;

    create or replace
    TYPE PROD_OBJ AS OBJECT (

       ID_PROD              NUMBER(6,0),
       NOME_PROD            VARCHAR2(100),        
       PREC_COMPRA_PROD     NUMBER(10,2),         
       PREC_VENDA_PROD      NUMBER(10,2),         
       QTD_STOCK_PROD       NUMBER(10),
       QTD_STOCK_MIN_PROD   NUMBER(10),
       IVA_PROD             NUMBER(6,2)
    );

/
create or replace
type PRODTABLE as table of PROD_OBJ;
/
create or replace type FORNEC_OBJ as object (
   ID_FORNECEDOR        NUMBER(6) ,
   NOME_FORNECEDOR      VARCHAR2(100) ,
   MORADA               VARCHAR2(300),
   ARMAZEM              VARCHAR2(300),
   EMAIL                VARCHAR2(30),
   TLF                  NUMBER(30) ,
   TLM                  NUMBER(30),
   FAX                  NUMBER(30)
   ); 
/

The problem is that I'm trying to get a list of products for each supplier, from table FORNECPRODS, but I can't (my idea was to return a struct like an hash with :list_of_products). To try that, I used this code only to print products from each supplier:

declare
    v_products    prodtable;
    TYPE t_supplier is TABLE OF FORNEC_OBJ;
    v_supplier           t_supplier;

begin
    select supplier bulk collect into v_supplier from fornecprods;
    for j in v_supplier.first.. v_supplier.last
    loop
        select products into v_products
        from fornecprods where supplier = v_supplier(j);
        dbms_output.put_line('-----------------------');
        dbms_output.put_line('Products list of ' || v_supplier(j).NOME_FORNECEDOR);
        dbms_output.put_line('-----------------------');
        for i in v_products.first .. v_products.last
        loop
            dbms_output.put(v_products(i).NOME_PROD);
        end loop;
    end loop;
end;

but it returned no data found for the first select.

so, could someone please help me find a way to retrieve a list (prodtable) from oracle to java? I already have the class to map a supplier and a product, I even passed an array of each of them from java to oracle, so they're good, I only need my j-tree to look like this:

SUPPLIERS
->SUPPLIER1
-prod1
-prod2
- ...
->SUPPLIER2
-prod1
-prod2
- ....

Is it possible to retrieve allt hat info like an hash of supplier:list_of_products with my current table and types?

Tks in advance

Answer 1

Hi newbAna,

First I would suggest against permanently storing nested tables in the database. While objects types can be really useful for variables and temporary results, you will find that nested tables tend to complicate SQL queries, add overhead and in general produce code that is less maintainable than regular relational normalized designs.

Now for your problem, first let's populate your table:

SQL> DECLARE
  2     l_prodtable prodtable := prodtable();
  3  BEGIN
  4     l_prodtable.extend(2);
  5     l_prodtable(1) := prod_obj(1, 'Prod A', '', '', '', '', '');
  6     l_prodtable(2) := prod_obj(2, 'Prod B', '', '', '', '', '');
  7     FOR i IN 1 .. 2 LOOP
  8        INSERT INTO fornecprods VALUES (fornec_obj(i, 'Forn '||i, '',
  9                                                   '', '', '', '', ''),
 10                                        l_prodtable);
 11     END LOOP;
 12  END;
 13  /     
PL/SQL procedure successfully completed

You would then loop through the elements rather simply:

SQL> BEGIN
  2     FOR cc IN (SELECT supplier, products FROM fornecprods) LOOP
  3        dbms_output.put_line('-----------------------');
  4        dbms_output.put_line('Products list of '
  5                             || cc.supplier.NOME_FORNECEDOR);
  6        dbms_output.put_line('-----------------------');
  7        FOR i IN 1 .. cc.products.count LOOP
  8           dbms_output.put_line('-' || cc.products(i).NOME_PROD);
  9        END LOOP;
 10     END LOOP;
 11  END;
 12  /

-----------------------
Products list of Forn 1
-----------------------
-Prod A
-Prod B
-----------------------
Products list of Forn 2
-----------------------
-Prod A
-Prod B

PL/SQL procedure successfully completed

Answer 2

@Vincent Malgrat: Thanks, your tip really worked for me! I rearranged my code and came up with this function: create or replace

function getAllSuppliersObjects RETURN FORNECTABLE AS
  suppliersList FORNECTABLE := FORNECTABLE();

BEGIN
     FOR res IN (SELECT supplier, products FROM fornecprods) LOOP
        /*dbms_output.put_line('-----------------------');
        dbms_output.put_line('Existent suppliers: '
                             || res.supplier.NOME_FORNECEDOR);*/
        suppliersList.extend;
        suppliersList(suppliersList.last):= res.supplier;
     END LOOP;
     return suppliersList;
  END;