TracGantt Pluginの開始日/終了日で,チケットをソートする

SELECT p.value AS __color__,
   (CASE status
     WHEN 'assigned' THEN '速攻で片付けろ' 
     ELSE '分割してからAssignしろ' 
    END) AS __group__,
   id AS ticket, summary, component, 
   (CASE status WHEN 'assigned' THEN owner||' *' ELSE owner END) AS owner,
   changetime AS _changetime, description AS _description,
   reporter AS _reporter,
  (CASE WHEN c.value = 'YYYY/MM/DD' THEN 'None' ELSE c.value END) AS 開始日,
  (CASE WHEN d.value = 'YYYY/MM/DD' THEN 'None' ELSE d.value END) AS 終了日
  FROM ticket t
     LEFT OUTER JOIN ticket_custom c ON (t.id = c.ticket AND c.name = 'due_assign')
     LEFT OUTER JOIN ticket_custom d ON (t.id = d.ticket AND d.name = 'due_close')
  LEFT JOIN enum p ON p.name = t.priority AND p.type = 'priority'
  WHERE status IN ('new', 'assigned', 'reopened') 
  ORDER BY (status = 'assigned') DESC, d.value, c.value, p.value