返回两个表查询后的记录差异
SELECT   SALES.SALE_ID   as   bysale
FROM   SALES
WHERE   saledate> '2007-08-01 '   and   saledate < '2007-09-1 '
共有19882行记录

select   distinct(salesproduct.sale_id)   as   bysalesproduct
from   salesproduct,sales
WHERE   saledate> '2007-08-01 '   and   saledate < '2007-09-1 'and
sales.sale_id=salesproduct.sale_id
共有19879行记录

用什么方法显示差异的3条数据的单号或者详细资料，saleproduct   表不包括日期

------解决方案--------------------
SELECT * FROM SALES
WHERE saledate> '2007-08-01 ' and saledate < '2007-09-1 '
and SALE_ID not in
(
select distinct(salesproduct.sale_id) as bysalesproduct
from salesproduct,sales
WHERE saledate> '2007-08-01 ' and saledate < '2007-09-1 'and
sales.sale_id=salesproduct.sale_id
)