Oracle - 从SYS_REFCURSOR中选择的pl sql

Question

I have a function that returns a SYS_REFCURSOR that has a single row but multiple columns. What I'm looking to do is to be able to have a SQL query that has nested sub-queries using the column values returned in the SYS_REFCURSOR. Alternative ideas such as types, etc would be appreciated. Code below is me writing on-the-fly and hasn't been validated for syntax.

--Oracle function
CREATE DummyFunction(dummyValue AS NUMBER) RETURN SYS_REFCURSOR
IS
  RETURN_DATA SYS_REFCURSOR;
BEGIN
  OPEN RETURN_DATA
  SELECT
    TO_CHAR(dummyValue) || 'A' AS ColumnA
    ,TO_CHAR(dummyValue) || 'B' AS ColumnB
  FROM
    DUAL;

  RETURN RETURN_DATA;
END;

--sample query with sub-queries; does not work
SELECT
  SELECT ColumnA FROM DummyFunction(1) FROM DUAL AS ColumnA
  ,SELECT ColumnB FROM DummyFunction(1) FROM DUAL AS ColumnB
FROM
  DUAL;

Answer 1

A SYS_REFCURSOR won't work for the intended use - you need to create an Oracle TYPE:

CREATE TYPE your_type IS OBJECT (
  ColumnA VARCHAR2(100),
  ColumnB VARCHAR2(100)
)

Update your function:

CREATE DummyFunction(dummyValue AS NUMBER) 
RETURN your_type
IS

BEGIN

  INSERT INTO your_type
  SELECT TO_CHAR(dummyValue) || 'A' AS ColumnA,
         TO_CHAR(dummyValue) || 'B' AS ColumnB
    FROM DUAL;

  RETURN your_type;

END;

Then you can use:

SELECT (SELECT ColumnA FROM table(DummyFunction(1))) AS ColumnA, 
       (SELECT ColumnB FROM table(DummyFunction(1))) AS ColumnB
  FROM DUAL

The example is overcomplicated - all you need to use is:

SELECT x.columna,
       x.columnb
  FROM table(DummyFunction(1)) x