In T-SQL, I use this query to get the Partition Schema Number. I'm partitioning on a date column in the partition table.

SELECT

$partition.OrderDetailDatePartitionFunction(o.<date column>)

AS [Partition Number]

FROM dbo.<partition table name> AS o

WHERE o.<table key> = (SELECT MIN(o1.<table Key>)

FROM dbo.<partition table name> AS o1

WHERE o1.<date column> =

(SELECT min(o2.<date column>) FROM dbo.<partition table name> AS o2)) ;

My test partition table looks likwe this:

CREATE TABLE [dbo].[OrderDetail](

[OrderDetailKey] [int] IDENTITY(1,1) NOT NULL,

[OrderDetailDate] [datetime] NOT NULL,

[Quantity] [int] NOT NULL,

CONSTRAINT [OrdersPK] PRIMARY KEY CLUSTERED

(

[OrderDetailDate] ASC,

[OrderDetailKey] ASC

)

and the query looks like this:

SELECT

$partition.OrderDetailDatePartitionFunction(o.OrderDetailDate)

AS [Partition Number]

FROM dbo.OrderDetail AS o

WHERE o.OrderDetailKey = (SELECT MIN(o1.OrderDetailKey)

FROM dbo.OrderDetail AS o1

WHERE o1.OrderDetailDate =

(SELECT min(o2.OrderDetailDate) FROM dbo.OrderDetail AS o2)) ;