Question

I have a question regarding a unified insert query against tables with different data
structures (Oracle). Let me elaborate with an example:

    tb_customers (
    id NUMBER(3), name VARCHAR2(40), archive_id NUMBER(3)
    )

    tb_suppliers (
    id NUMBER(3), name VARCHAR2(40), contact VARCHAR2(40), xxx, xxx, 
    archive_id NUMBER(3)
    )

The only column that is present in all tables is [archive_id]. The plan is to create a new archive of the dataset by copying (duplicating) all records to a different database partition and incrementing the archive_id for those records accordingly. [archive_id] is always part of the primary key.

My problem is with select statements to do the actual duplication of the data. Because the columns are variable, I am struggling to come up with a unified select statement that will copy the data and update the archive_id.

One solution (that works), is to iterate over all the tables in a stored procedure and do a:

CREATE TABLE temp as (SELECT * from ORIGINAL_TABLE);
UPDATE temp SET archive_id=something;
INSERT INTO ORIGINAL_TABLE (select * from temp);
DROP TABLE temp;

I do not like this solution very much as the DDL commands muck up all restore points.

Does anyone else have any solution?

Answer 1

How about creating a global temporary table for each base table?

create global temporary table tb_customers$ as select * from tb_customers;
create global temporary table tb_suppliers$ as select * from tb_suppliers;

You don’t need to create and drop these each time, just leave them as-is.

You’re archive process is then a single transaction…

insert into tb_customers$ as select * from tb_customers;
update tb_customers$ set archive_id = :v_new_archive_id;
insert into tb_customers select * from tb_customers$;

insert into tb_suppliers$ as select * from tb_suppliers;
update tb_suppliers$ set archive_id = :v_new_archive_id;
insert into tb_suppliers select * from tb_suppliers$;

commit; -- this will clear the global temporary tables

Hope this helps.