SELECT a.编码, a.编码 AS 编号, iif(a.部件名称 is null and a.零件名称 is null,a.主机名称,iif(a.零件名称 is null,a.部件名称,a.零件名称)) AS 名称, "" AS 小件编号, "" AS 小部件名称
FROM 表1 as a
UNION ALL SELECT b.编号 AS 编码, "" as 编号,"" AS 名称, b.编号 AS 小件编号, b.名称 AS 小部件名称
FROM 表2 as b
ORDER BY 编码, 编号 DESC , 小部件名称;