怎么运用联合查询求每日库存量和期初量?

SELECT 日期, 产品名称, 期初数量, 期初金额, 0 AS 进货数量,0 AS 进货单价, 0 AS 进货金额,0 AS 销售数量,0 AS 销售单价, 0 AS 销售金额
FROM qryqc
union all
select 日期,产品名称, 0 as 期初数量,0 AS 期初金额, 进货数量,进货单价, 进货金额,0 as 销售数量 , 0 AS 销售单价,0 AS 销售金额 from qrygj
UNION ALL select 日期, 产品名称,0 as 期初数量, 0 AS 期初金额,0 as 进货数量,0 AS 进货单价,0 AS 进货金额, 销售数量, 销售单价,销售金额 from qryxs;