insert #b
select * from tb a
where 到货时间=(select min(到货时间) from tb b 
where a.物料=b.物料  and a.供应商=b.供应商)

------解决方案--------------------
SQL code
select * into #b
from tb t
where not exists(select 1 from tb where 物料=t.物料 and 供应商=t.供应商 and 到货时间<t.到货时间)

------解决方案--------------------
SQL code
select * from tb t where not exsits(select 1 from tb where 供应商=t.供应商 and 到货时间<t.到货时间)

------解决方案--------------------
SQL code

select a.供应商,a.物料,b.到货时间
from tb a outer apply(
      select top 1 到货时间 from tb where 供应商 = a.供应商 and 物料 = a.物料 order by 到货时间
    ) b