Ich glaube, diese Unterabfrage wird es tun (nicht getestet).
select *,
(select top 1 Discount
from table2
where table2.Date <= t.Date
order by table2.Date desc) as Discount
from Table1 t
Vielleicht aber nicht die leistungsfähigste.
Bearbeiten:
Testcode:
create table #table1 ([date] datetime, val int)
create table #table2 ([date] datetime, discount int)
insert into #table1 ([date], val) values ('1/26/2010', 10)
insert into #table1 ([date], val) values ('1/25/2010', 9)
insert into #table1 ([date], val) values ('1/24/2010', 8)
insert into #table1 ([date], val) values ('1/24/2010', 9)
insert into #table1 ([date], val) values ('1/23/2010', 7)
insert into #table1 ([date], val) values ('1/22/2010', 10)
insert into #table1 ([date], val) values ('1/21/2010', 11)
insert into #table2 ([date], discount) values ('1/26/2010', 2)
insert into #table2 ([date], discount) values ('1/23/2010', 1)
insert into #table2 ([date], discount) values ('1/20/2010', 0)
select *,
(select top 1 discount
from #table2
where #table2.[date] <= t.[date]
order by #table2.[date] desc) as discount
from #table1 t
drop table #table1
drop table #table2
Ergebnisse:
