エラー＃1054-'NEWの不明な列'program_id'

CREATE TRIGGER trig_job_color tb_jobsに挿入した後 FOR EACH ROW BEGINSET @program_id =（tb_ticketsからprogram_idを選択します。tb_tickets.job_id=NEW.job_id）;

SET @newstatus = (Select status from tb_tickets
where tb_tickets.job_id = NEW.job_id);
SET @newsite_id = (Select site_id from tb_tickets
where tb_tickets.job_id = NEW.job_id);

CASE @program_id
 WHEN 1 THEN
   UPDATE tb_sites_3 
   SET tb_sites_3.color_status = @newstatus 
   WHERE tb_sites_3.site_id = @newsite_id;
 WHEN 2 THEN
   UPDATE tb_sites_3 
   SET tb_sites_3.color_status = @newstatus 
   WHERE tb_sites_3.site_id = @newsite_id;
 WHEN 3 THEN
   UPDATE tb_sites_3
   SET tb_sites_3.color_status = @newstatus 
   WHERE tb_sites_3.site_id = @newsite_id;
 END CASE;
 END