I simply want a stored procedure that calculates a unique id and inserts it. If it fails it just calls itself to regenerate said id. I have been looking for an example, but cant find one, and am not sure how I should get the sp to call itself, and set the appropriate output parameter. I would also appreciate someone pointing out how to test this sp also.

ALTER PROCEDURE [dbo].[DataContainer_Insert] 
@SomeData varchar(max),
@DataContainerId int out    
AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements.
    SET NOCOUNT ON;
    BEGIN TRY
        SELECT @UserId = MAX(UserId) From DataContainer
        INSERT INTO DataContainer (UserId, SomeData)
        VALUES (@UserId, SomeData)

        SELECT @DataContainerId = scope_identity()
    END TRY
    BEGIN CATCH
        --try again
        exec DataContainer_Insert @DataContainerId, @SomeData
    END CATCH       

END