Migrating elemental from a subclass of Page to Page

isuckatsql.sql

# Assumes the first non-zero ElementalAreaID in the versions table is the correct one to use
# (because they basically never change). Swap out table names as appropriate for your class.
# Don't forget to update Page_Live too!

UPDATE Page p
INNER JOIN
(
  SELECT RecordID, ElementalAreaID
  FROM CaseStudyPage_Versions
  WHERE ElementalAreaID > 0
  GROUP BY RecordID, ElementalAreaID, Version
  ORDER BY Version ASC
) c
ON p.ID = c.RecordID
SET p.ElementalAreaID = c.ElementalAreaID
WHERE c.RecordID IS NOT NULL;