>I have a stored procedure called ap_LookupPart. It must be provided a warehouse Id and a part no. The Serial number is optional. If I don't pass a serialno, no data is returned. I don't understand why this isn't working:
>
>

>CREATE PROCEDURE ap_LookupPart
>	@WarehouseId	INT,
>	@PartNo		VARCHAR(30),
>	@SerialNo	VARCHAR(30) = NULL
>	
>AS
>BEGIN
>
>	SELECT i.*, p.PartNo, p.Description, l.Location, w.WarehouseCode, w.Caption AS Warehouse
>		FROM Inventory i
>		JOIN Parts p ON p.PartId = i.PartId
>		JOIN Locations l ON l.LocationId = i.LocationId
>		JOIN Warehouses w ON w.WarehouseId = i.WarehouseId
>		WHERE w.WarehouseId = @WarehouseId AND
>			  p.PartNo = @PartNo AND
>			  i.SerialNo = ISNULL(@SerialNo, i.SerialNo)
>
>END
>

Is this works?

<pre>
CREATE PROCEDURE ap_LookupPart
	@WarehouseId	INT,
	@PartNo			VARCHAR(30),
	@SerialNo		VARCHAR(30) = NULL
	
AS
BEGIN

	SELECT i.*, p.PartNo, p.Description, l.Location, w.WarehouseCode, w.Caption AS Warehouse
		FROM Inventory i
		JOIN Parts p ON p.PartId = i.PartId
		JOIN Locations l ON l.LocationId = i.LocationId
		JOIN Warehouses w ON w.WarehouseId = i.WarehouseId
		WHERE w.WarehouseId = @WarehouseId AND
                      p.PartNo      = @PartNo

END

BTW how you call this SP?