StudeStude> Scenario - C# Application + SQL Server 2008 R2

I have a table Currency with the following structure

```
currencyID - int - NOT NULL - Primary Key - IS Identity (**True**)

currency - VARCHAR(50) - NOT NULL

```

1. Now , this currencyID is a foreign key in another table Student\_Payment\_Details.
2. The currency table is hosted in a ComboBox Control.
3. **I need a way to insert NULL (or nothing) in case no currency option is selected**. 
(e.g selectedIndex = -1)

> 
> *Been reading articles stating that it's against all SQL rules to insert a NULL for a foriegn key while its bound to a primary NOT NULL key in the master table*
> 
> 
> 

**So, guys, i need your suggestions for a workaround. Thank you in advance.**

* Here's a trimmed version of my stored procedure

CREATE PROCEDURE [dbo].[spStudentPaymentDetails] 

```
    -- PARAMETERS
    **** blah blah ***
    @currencyID int = null,
    @studentFees varchar(100) = null,
    **** blah blah ***
AS
BEGIN
    SET NOCOUNT ON;
            -- Add Student Details
            INSERT INTO Student_Payment_Details(****,currencyID,studentFees,****) values(****,@currencyID,@studentFees,****);
            SELECT SCOPE_IDENTITY();    
END

```