Modify a nested table in Oracle - oracle

Question

I have the below Nested table created :
create or replace TYPE access_t AS OBJECT (
AccessID VARCHAR2(50),
Eligibility char(1)
);
/
create or replace TYPE Access_tab IS TABLE OF access_t;
/
create or replace TYPE add_t AS OBJECT (
city VARCHAR2(100),
state VARCHAR2(100),
zip VARCHAR2(10),
APOINTSARRAY Access_tab )
;
/
create or replace TYPE add_tab IS TABLE OF add_t;
/
CREATE TABLE RQST_STATUS
( RQST_ID NUMBER,
ADDRESS add_tab
)
NESTED TABLE ADDRESS STORE AS RQST_STATUS_ADDRESS
( NESTED TABLE APOINTSARRAY STORE AS RQST_STATUS_AP)
;
If i need to change ADDRESS type to new_add_tab with some additional columns instead of add_tab , Can i just use ALTER TABLE .. MODIFY .. command ?
I am getting ORA-00922 or ORA-22913 errors . I cannot change the type directly because it is used somewhere else too. Also, the table is already loaded with data.
Please suggest.

Answer 1

You can do that but you have to alter the TYPE not the TABLE.
Check the documentation ALTER TYPE Statement: alter_method_spec
Most important is the CASCADE key word.
Examples:
ALTER TYPE access_t ADD ATTRIBUTE NEW_Eligibility INTEGER CASCADE;
ALTER TYPE access_t DROP ATTRIBUTE Eligibility CASCADE;
ALTER TYPE access_t MODIFY ATTRIBUTE AccessID VARCHAR2(100) CASCADE;

Answer 2

Here is a step-by-step description of my suggestion. It might not be the most elegant, but I think that it would be best for you to have something you can fully understand (as opposed to an obscure trick).
Also, and since I don't really know what kind of changes you need to do for the internal table, I'm leaving the maximal flexibility for you to do any change you may wish to do.
Let's call your table T1 that contains a columns C_T which is your internal table.
The internal table contains columns C_1, C-2 and C_3, and you want the new structure for the record to be D_1, D_2, D_3, D_4 and D_5, where the mapping is:
C_1 -> D_5,
C_2 -> D_1,
C_3 -> D_2,
{new} -> D_3,
{new} -> D_4.
Create a tempo table TEMPO_T with a column SOURCE_ROWID (varchar2(64)) and the new columns D_1,..., D5.
Write a small anonymous block having a cursor that selects the ROWID of each row of table T1 and all the records within the internal table in column C_T (order by ROWID). The result would look like (this is just an example of course):
ROWID C_1 C_2 C_2
wwereeedffff 1 a ww
wwereeedffff 2 b xx
wwereeedffff 7 l yy
ertrtrrrtrrr 5 d PP
ertrtrrrtrrr 99 h mm
...
[Note: The use of ROWID is under the assumption that you don't have a column that can serve as a unique identifier for each row in table T1; if there is such column - one defined as UNIQUE INDEX - you can use that field instead]
Having this query ready, convert it into an INSERT into the temporary table TEMPO_T along with whatever values you need to store for columns D_3 and D_4.
Now, you have a backup of the original contents of column C_T and hence can delete the column.
Now, you can update the type that defines the structure of column C_T to its new form (i.e. D_1,...,D_5) and alter table T1 by adding a column whose type is the updated one.
Finally, you can insert the contents of column C_T with that stored in the temporary table (since you already have this, I assume that you know how to implement it - inserting a table within a cell column of the outer table).
That's it.
Needless to say, I would make a backup of your data before engaging into this.
Hope this description is detailed enough to enable you to complete the task at hand.