return resultset from function

Question

I need to return a resultset from function and work with this resultset just like with an ordinary table.

So I need something like following:

select          


        

Answer 1

If I understand you correctly, you want to do this:

select * from (select * from dual)

...with the caveat that the subquery is in some way dynamic? You can do this using a PL/SQL block, using a reference cursor:

declare
  subQuery         varchar2(1000);
  mainQuery        varchar2(1000) := 'select * from (';

  type myRefCursor is ref cursor;
  myResultset      myRefCursor;

  myField1         FIELDTYPE;
  ...
  myFieldN         FIELDTYPE;
begin
  -- Generate this dynamically
  subQuery := 'select * from dual';

  -- Create main query and open cursor
  mainQuery := mainQuery || subQuery || ')';
  open myResultset for mainQuery;

  -- Loop through records
  loop
    fetch myResultset into myField1, ..., myFieldN;
    exit when myResultset%NOTFOUND;

    -- Do something with the record data
    dbms_output.put_line(myField1 || ' ... ' || myFieldN);
  end loop;

  close myResultset;
end;
/

Note that rather than using fetch into with individual variables, you can populate an entire record at once, provided you can define the record's field types. That is, if you have created a custom type or your record's type matches a table you already have in your schema. For the latter, you can use:

myRecord someTable%ROWTYPE;

...in the declaration block, then change the fetch into statement to:

fetch myResultset into myRecord;

...and access record fields using dot notation (e.g., myRecord.some_field_name).

You say in your comments that the dynamic SQL bit is from the results of some other query. Therefore, in my example code, you could use a regular cursor to loop over these data to create the subQuery variable in each instance... Although, incidentally, is there any reason why what you're trying to achieve can't be done with a simple join?