I don't see a problem in this procedure just by looking at it. I believe the logic is written correctly, so it's very puzzling.

>yes and yes.
>
>The problem is not what's being passed to the proc, it's that batchid is always being incremented inside the proc. What's being
>passed is always the last value sent back out, where for a series of calls it should be the same.
>
>
>
>
>
>
>>Did you test this from SSMS? Did you try addint print @BatchID at the top of the procedure?
>>
>>>In this proc I pass in 0 or a BatchId from a previous run. If a batchId is passed, I want to use it, otherwise, compute the next
>>>batch Id and use that.
>>>
>>>This is alwats incrementing the batch Id. I don't see what's wrong.
>>>
>>>
>>>

>>>
>>>CREATE PROCEDURE ap_AddInventoryRecord
>>>	@PartId			INT = NULL,	
>>>	@WarehouseId	INT = NULL,
>>>	@LocationId		INT = NULL,
>>>	@UserId			INT = NULL,
>>>	@SerialNo		VARCHAR(30) = NULL,
>>>	@Quantity		INT = 1,
>>>	@DropShip		TINYINT = NULL,
>>>	@Printed		TINYINT = NULL,
>>>	@ActionDate		DATETIME = NULL,
>>>	@PurchaseOrder	VARCHAR(30) = NULL,
>>> 	@Comments		TEXT = NULL,
>>>	@InventoryId	INT = NULL OUTPUT,
>>>	@BatchId		INT OUTPUT
>>>
>>>AS
>>>BEGIN
>>>
>>>	IF @ActionDate IS NULL
>>>		BEGIN
>>>			SET @ActionDate = GETDATE()
>>>		END
>>>
>>>	IF(@BatchId IS NULL OR @BatchId = 0)
>>>		BEGIN
>>>			SELECT @BatchId = MAX(BatchId) + 1 FROM Inventory
>>>		END
>>>
>>>	IF(@BatchId IS NULL)
>>>		BEGIN
>>>			SET @BatchId = 1
>>>		END
>>>
>>>	INSERT INTO Inventory
>>>		(BatchId, PartId, WarehouseId, LocationId, UserId, SerialNo, Quantity,
>>>		DropShip, Printed, ActionDate, PurchaseOrder, Comments)
>>>		VALUES
>>>		(@BatchId, @PartId, @WarehouseId, @LocationId, @UserId, @SerialNo, @Quantity, 
>>>		@DropShip, @Printed, @ActionDate, @PurchaseOrder, @Comments)
>>>	
>>>	SET @InventoryId = SCOPE_IDENTITY()
>>>
>>>END
>>>