Help with Oracle PL/SQL and Objects...

Question

Hi,
I wonder if you can help me, I am having some trouble dealing with Oracle objects in PL/SQL. I can declare them, populate them and read from them without any issues.
But I am having some problems with trying to copy records in to other records of the same type, and also with updating existing records. I've made a mock up piece of code below to explain what I mean, it may have a few mistakes as I've written it in notepad but should be reasonably clear.
First I have created a record type, which contains attributes relating to a person.....
CREATE OR REPLACE
TYPE PERSON_RECORD_TYPE AS object (
                    Person_ID          NUMBER(3),
                    Person_Name     VARCHAR(20),
                    Person_Age          NUMBER(2),
                    static function new return PERSON_RECORD_TYPE );
CREATE OR REPLACE
TYPE BODY PERSON_RECORD_TYPE as
static function new return PERSON_RECORD_TYPE is
BEGIN
return PERSON_RECORD_TYPE (
     NULL,
                         NULL,
                         NULL,
                         NULL,
                         NULL
END;
END;
Then I have created a table type, which is a table of the person record type......
CREATE OR REPLACE
type PERSON_TABLE_TYPE as table of PERSON_RECORD_TYPE;
Finally I have created a procedure which recieves an instance of the person table type and reads through it using a cursor.....
PROCEDURE ADMIN_PERSON (incoming_person     IN     PERSON_TABLE_TYPE)
IS
-- This is a local record declared as the same type as the incoming object
local_person PERSON_TABLE_TYPE;
-- Cursor to select all from the incoming object
CURSOR select_person
IS
SELECT      *
FROM      TABLE ( cast (incoming_person AS PERSON_TABLE_TYPE));
BEGIN
-- Loop to process cursor results
FOR select_person_rec IN select_person
     LOOP
          /* Up to this point works fine...*/
          -- If I want to store the current cursor record in a local record of the same type, I can do this....
          local_person.person_id          := select_person_rec.person_id;
          local_person.person_name      := select_person_rec.person_name;
          local_person.person_age          := select_person_rec.person_age;
-- QUESTION 1
          -- The above works fine, but in my real example there are a lot more fields          
          -- Why cant I set the local record to the value of the cursor record like this below..     
          local_person := select_person_rec;
-- The above line gives a pl/sql error - expression is of wrong type, (as far as I can see the records are of the same type?)
-- QUESTION 2
          --Also how do you update an existing record within the original object, I have tried the following but it does not work
          UPDATE incoming_person
          SET          age = (age + 1)
          WHERE     incoming_person.person_id = '123';
-- The error here is that the table does not exist
     END LOOP;
END;
So I hope that you can see from this, I have two problems. The first is that I can store the current cursor record in a local record if I assign each attribute one at a time, but my real example has a large number of attributes. So why can't I just assign the entire cursor record to the local cursor record?
I get a PL/SQL error "Expression is of wrong type" when I try to do this.
The second question is with regards to the update statement, obviously this doesn't work, it expects a table name here instead. So can anyone show me how I should update existing person records in the incoming table type to the procedure?
I hope this makes sense, but I don't think I have explained it very well!!
Any help will be gratefully recieved!!
Thanks

Answer 1

I understand why you are having trouble - my own brain started to hurt looking at your questions :)
First off, database types are not records. They can act like records but are "objects" with different characterstics.
You can create a record in PL/SQL but the "type" is of RECORD. You created an OBJECT as BODY_PERSON_RECORD_TYPE.
I don't use database types unless I really need them, such as for working with pipelined functions.
-- QUESTION 1
-- The above works fine, but in my real example there are a lot more fields
-- Why cant I set the local record to the value of the cursor record like this below..
local_person := select_person_rec; local_person is set to the (misnamed) BODY_PERSON_RECORD_TYPE, while SELECT_PERSON_REC is anchored to the cursor and is a RECORD of SELECT_PERSON%ROWTYPE with a field for each column selected in the query. Different types, not compatible.
You should be able to manually assign the object items one by one as object.attribute := record.field one field at a time.
-- QUESTION 2
--Also how do you update an existing record within the original object, I have tried the following but it does not workCheck the on-line documentation for the syntax. You'll probably have to reference the actual value through the table; this is one reason why I don't work with nested tables - the syntax to do things like updates is much more complex.