下面是正解 用 is null
(case when dbo.Feedback.Funnel is null then '否' when dbo.Feedback.Funnel='否' then '是' when dbo.Feedback.Funnel= '是' then '是' end) as Funnel,
(case when dbo.Feedback.Callout is null then '否' when dbo.Feedback.Callout= '否' then '是' when dbo.Feedback.Callout= '是' then '是' end) as Callout
下面個人筆記記錄優化，與此標題無關（只要提交一個都標記為已提交）
(CASE WHEN dbo.Feedback.Callout = '否' OR
dbo.Feedback.Callout = '是' OR
dbo.Feedback.Funnel = '否' OR
dbo.Feedback.Funnel = '是' THEN '是' ELSE '否' END) AS isFeedback