Find All Recent Winners and Calculate an Encoding of What They Won

Question

Context

I was proud of this code for a little while, but the repetition wounds me. I know that the function name sucks, but the name and interface to this function are not under my control. Performance is not a concern. Note that this must be an inline table-valued function.

Fixing the repetition is my only concern. How can I reduce it?

This is a follow-up from this question. You do not and should not need to read that question first. This question exists because I oversimplified that one.

Dependencies

CREATE TABLE [WINNERS]
(
  WINNER_ID INT NOT NULL
  AMOUNT INT NOT NULL
);

CREATE TABLE [RelevantWinners]
(
  WINNER_ID INT NOT NULL
);

INSERT INTO [WINNERS]
  VALUES (1, 20), (2, 30), (3, 309), (4, 50), (5, 50);

INSERT INTO [RelevantWinners]
  VALUES (1), (5);

The Code For Review

CREATE FUNCTION RecentWinners
(
  @GetAllWinners BIT
)
RETURNS TABLE
AS
RETURN
(
-- Style note: I've yet to figure out how to best indent consecutive CTEs.
WITH
  [WinnersRelevant] AS
  (
    SELECT
      -- The inclusion of a silly calculation is deliberate.  
      2 * [Win].[AMOUNT] + 47 [ENCODING]
    FROM
      [Winners] [Win]
    WHERE EXISTS
      (
          SELECT 1
          FROM [RelevantWinners] [Rev]
          WHERE [Rev].[WINNER_ID] = [Win].[WINNER_ID]
      )
  ),
  [WinnersAll] AS
  (
      -- This is the first major repetition.
      -- It's exactly the same code as before, but without the semi-join.
    SELECT
      2 * [Win].[AMOUNT] + 47 [ENCODING]
    FROM
      [Winners] [Win]
  )
    SELECT
      [ENCODING],
      -- The inclusion of a second silly calculation is deliberate.
      2 * [ENCODING] + 12346 [ENCODING_2]
    FROM
      [WinnersRelevant]
    WHERE
      @GetAllWinners = 0

 UNION ALL
      -- This is the second major repetition.
      -- It's exactly the same SELECT list as before.
    SELECT
      [ENCODING],
      2 * [ENCODING] + 12346 [ENCODING_2]
    FROM 
      [WinnersAll]
    WHERE
      @GetAllWinners = 1
); --I'm pretty sure this is the only relevant semicolon, even under strict standards.

DB Fiddle.

Answer 1

Just lump another sub-predicate beside your exists:

create function RecentWinners(@GetAllWinners bit)
returns table
as return (
  select encoding,
         2*encoding + 12346 as encoding_2
  from (
    select 2*amount + 47 as encoding
    from Winners
    where @GetAllWinners=1 or exists (
      select 1 from RelevantWinners as rw
      where rw.winner_id = Winners.winner_id
    )
  ) as WinnersAggregate
);

I don't care much for shouting, hence the lowercase.