How to migrate 'table' data type into oracle solution?

Question

Say, I have following sample code in Sql Server:
Declare @v1 table(old_value int, new_value int)
insert into @v1 select old_value, new_value from aTable where....
declare cur cursor for
select new_value from @v1 where old_value=...
what should I use in oracle to convert above code? I was thinking about nested table, but it seems not very suitable here. Any better solutions out there?

Answer 1

It's been a while since I've done any SQL Server development, but if I recall correctly, a table data type in Transact SQL is used for storing temporary result sets.
In your example, you seem to be temporaily storing the results of a query in a Transact SQL table, and then opening a cursor to iterate over the results.
In Oracle PL/SQL, there is usually no need to do this, just open a cursor:
create or replace procedure test_proc as
begin
for curs_rec in (select old_value, new_value from myTable) loop
... process each row ...
end loop;
end test_proc;
If you really want your results in an array which your code can iterate over, look into the BULK COLLECT clause of the SELECT statement:
create or replace procedure test_proc as
TYPE array_type IS TABLE of myTable%ROWTYPE INDEX BY BINARY_INTEGER;
my_array array_type;
begin
SELECT * BULK COLLECT INTO my_array FROM myTable;
for idx in my_array.FIRST..my_array.LAST loop
dbms_output.put_line(my_array(idx).col1);
end loop;
end test_proc;
Note that I have not actually compiled the above code, so there may be syntax errors :)
Also, prior to 9i you can not BULK COLLECT into a table based on a rowtype (you need to created an array for each attribute).
SQL Server also allows function which return table types. This is similar to PL/SQL pipelined table functions (available in 9i and higher - see the PL/SQL guide), which can be used to materialize rows which can be processed like any other result set.
SQL Server also has a concept of temporary tables which is totally different than Oracle's temporary tables. SQL Server developers must often resort to using temporary tables in their stored procedures; in Oracle, this is rarely necessary.