Customize PL/SQL exceptions in Oracle

Question

Frequently I found myself doing some functions to insert/delete/update in one or more tables and I've seen some expected exceptions been taken care of, like no_data_found, dupl_val_on_index, etc. For an insert like this:

create or replace FUNCTION          "INSERT_PRODUCTS" (

  a_supplier_id IN FORNECEDOR.ID_FORNECEDOR%TYPE,

  a_prodArray IN OUT PRODTABLE

  )

 RETURN NUMBER IS

    v_error_code    NUMBER;
    v_error_message VARCHAR2(255);
    v_result        NUMBER:= 0;
    v_prod_id       PRODUTO.ID_PROD%TYPE;
    v_supplier      FORNECEDOR%ROWTYPE;
    v_prodInserted  PROD_OBJ;
    newList prodtable := prodtable();

 BEGIN

 SELECT  FORNEC_OBJ(ID_FORNECEDOR,NOME_FORNECEDOR,MORADA,ARMAZEM,EMAIL,TLF,TLM,FAX) into v_supplier from fornecedor where id_fornecedor = a_supplier_id;

  FOR i IN a_prodArray.FIRST .. a_prodArray.LAST LOOP

      INSERT INTO PRODUTO (PRODUTO.ID_PROD,PRODUTO.NOME_PROD,PRODUTO.PREC_COMPRA_PROD,PRODUTO.IVA_PROD,PRODUTO.PREC_VENDA_PROD,PRODUTO.QTD_STOCK_PROD,PRODUTO.QTD_STOCK_MIN_PROD)
      VALUES (S_PRODUTO.nextval,a_prodArray(i).NOME_PROD,a_prodArray(i).PREC_COMPRA_PROD,a_prodArray(i).IVA_PROD,NULL,NULL,NULL);

      /* If the above insert didn't failed, we can insert in weak entity PROD_FORNECIDO. */
      SELECT ID_PROD into v_prod_id from PRODUTO where NOME_PROD = a_prodArray(i).NOME_PROD;

      INSERT INTO PROD_FORNECIDO VALUES (a_supplier_id, v_prod_id,a_prodArray(i).PREC_COMPRA_PROD);

      SELECT PROD_OBJ(ID_PROD,NOME_PROD,PREC_COMPRA_PROD,PREC_VENDA_PROD,QTD_STOCK_PROD,QTD_STOCK_MIN_PROD,IVA_PROD) into v_prodInserted from PRODUTO where ID_PROD= v_prod_id;
      a_prodarray(i).ID_PROD := v_prod_id;

    END LOOP;

    INSERT INTO FORNECPRODS VALUES (a_supplier_id,v_supplier, a_prodarray);
    v_result:= 1;
    RETURN v_result;
    COMMIT;

Exception

When no_data_found then
    v_error_code := 0;
    v_error_message:= 'Insert Products: One of selects returned nothing';
    Insert Into errors Values (v_error_code,v_error_message, systimestamp);
    RETURN  v_result;

 When others Then
    ROLLBACK;
    v_error_code := SQLCODE;
    v_error_message:=substr(SQLERRM,1,50);
    Insert Into errors Values (v_error_code,'Error inserting products list',systimestamp);
    RETURN  v_result;

END;

I would like to customize more of my exceptions or do an exception block for each select/insert. Is that possible or correct?

If so, could please show me some code with important exceptions being throwed by this function?

Answer 1

• In the exception section; you can raise application error or return 0 with error code explanation. It is about your choice.

• If you want to log your errors in the exception section (or in main section), write your own logging procedure with AUTONOMOUS TRANSACTION. so, your logging mechanism is not affected by your main transaction's COMMIT or ROLLBACK. (see: http://www.dba-oracle.com/t_autonomous_transaction.htm)

• Another logging mechanism (DML Error Log) in Oracle 10gR2 (and above) is LOG ERRORS clause (see: http://www.oracle-base.com/articles/10g/DmlErrorLogging_10gR2.php).

Answer 2

If you just want to substitute your own error message, there is RAISE_APPLICATION_ERROR...

When no_data_found then
    RAISE_APPLICATION_ERROR(-20000
                             , 'Insert Products: One of selects returned nothing';
                             , true);

The third parameter returns the original error as well as your custom one.

Oracle also gives us the option to define our exceptions. This can be useful if we want to pass the exception to a calling program...

Declare
    no_product_found exception;
Begin
    ....
When no_data_found then
    raise no_product_found;

This would be most effective if we defined the NO_PRODUCT_FOUND exception in a package specification where it could be referenced by external program units.

In addition, Oracle provides the INIT_EXCEPTION pragma which allows us to associate Oracle error numbers with our custom exceptions. Unfortunately we cannot overload error numbers which Oracle has already defined (for instance, we cannot create our own exceptions for ORA-1403 which is already covered by the NO_DATA_FOUND exception). Find out more.