mysql - 2 つの同等のクエリを UNION ALL できませんか?

Question

数回繰り返す必要がある作業クエリがありますが、UNION ALL で構文エラーが発生します。

作業クエリ:

set @num := 0, @group := '';

select person, `group`, age
from 
(
   select person, `group`, age,
      @num := if(@group = `group`, @num + 1, 1) as row_number,
      @group := `group` as dummy
  from mytable
  order by `Group`, Age desc
) as x where x.row_number <= 2;

SQL フィドル

UNION ALL の失敗 (構文エラーを取得します):

set @num := 0, @group := '';
(
select person, `group`, age
from 
(
   select person, `group`, age,
      @num := if(@group = `group`, @num + 1, 1) as row_number,
      @group := `group` as dummy
  from mytable
  order by `Group`, Age desc
) as x where x.row_number <= 2;
)
UNION ALL
(
select person, `group`, age
from 
(
   select person, `group`, age,
      @num := if(@group = `group`, @num + 1, 1) as row_number,
      @group := `group` as dummy
  from mytable
  order by `Group`, Age desc
) as x where x.row_number <= 2;
)

SQL フィドル

(UNIONed クエリは、テスト目的で元のクエリを複製したものです)

Answer 1

余分なブラケットがあります。

このSQLフィドルを参照してください

Answer 2

set @num := 0, @group := '';

select person, `group`, age
from 
(
   select person, `group`, age,
      @num := if(@group = `group`, @num + 1, 1) as row_number,
      @group := `group` as dummy
  from mytable
  order by `Group`, Age desc
) as x where x.row_number <= 2
UNION ALL

select person, `group`, age
from 
(
   select person, `group`, age,
      @num := if(@group = `group`, @num + 1, 1) as row_number,
      @group := `group` as dummy
  from mytable
  order by `Group`, Age desc
) as x where x.row_number <= 2;

Answer 3

最も外側のかっこを削除します。SELECT ステートメントは、開き括弧ではなく、SELECT キーワードで開始する必要があります。