SELECT a.日期, a.产品, a.数量, first(价格)
FROM [SELECT a.日期, a.产品, a.数量, (b.价格)
FROM 出货 a left join 价格 b
on a.产品=b.产品 and a.日期>=b.日期]. AS [%$##@_Alias]
GROUP BY a.日期, a.产品, a.数量;
SELECT a.日期, a.产品, a.数量, first(价格)
FROM (SELECT a.日期, a.产品, a.数量, (b.价格)
FROM 出货 a left join 价格 b
on a.产品=b.产品 and a.日期>=b.日期) a
GROUP BY a.日期, a.产品, a.数量;