两个结构相同的表通过union连接称为一个表，然后在对新的表进行处理

  SELECT x.AssetId,SUM(x.Amount) AS Amount,AMS_assets.[name] 
  FROM (
  (   SELECT AMS_Plan_Item.asset_id as AssetId ,AMS_Plan_Item.amount AS Amount  FROM AMS_Plan_Item  INNER JOIN AMS_Plans_Normal t1 on t1.plan_id=AMS_Plan_Item.plan_id  WHERE 1=1   and t1.department_id='31b05701-60ef-405c-87ba-af47049e3f48'    AND AMS_Plan_Item.audit_status=1 )   
  union 
   ( SELECT AMS_Plan_Item.asset_id as AssetId ,AMS_Plan_Item.amount AS Amount FROM AMS_Plan_Item  INNER JOIN AMS_Plans_Urgent t1 on t1.plan_id=AMS_Plan_Item.plan_id   WHERE 1=1   and t1.department_id='31b05701-60ef-405c-87ba-af47049e3f48'   AND AMS_Plan_Item.audit_status=1  ) 

    ) x   

INNER JOIN AMS_assets ON AMS_assets.asset_id=x.AssetId GROUP BY x.AssetId,AMS_assets.[name]