use
[AdventureWorksDW2012]
go

;WITH sales AS (

select      d.OrderDateKey,
        SalesAmount = SUM(d.SalesAmount)
from        [dbo].[FactInternetSales] d
group by    d.OrderDateKey
having      SUM(d.SalesAmount)>10000
)

select  FirstOrderDateKey = MIN(OrderDateKey)

from sales