Mengembalikan NULL menggunakan WHERE IN

right outer join , left outer join , case dan juga not exists juga dapat dimanfaatkan. Beberapa contoh di bawah... (dengan tautan ke contoh kerja SQL Fiddle).

Hubungan luar kanan ke tabel sementara (pilih # UNION)

SELECT GROUP_CONCAT(CASE WHEN COLUMN1 IS NULL THEN "NULL" ELSE COLUMN1 END)
FROM archive
RIGHT OUTER JOIN
  (SELECT 21 AS id
   UNION SELECT 22 AS id) AS tmp ON tmp.id=archive.column2;

SQL Fiddle:http://sqlfiddle.com/#!2/805e1c/9

Hubungan luar kanan ke tabel ke-2

SELECT GROUP_CONCAT(
  CASE WHEN COLUMN1 IS NULL THEN "NULL" ELSE COLUMN1 END)
FROM archive
RIGHT OUTER JOIN temporary tmp ON tmp.id=archive.column2;

SQLFiddle:http://sqlfiddle.com/#!2/36fba/2