Optional parameter in the example below is @param3 with a default of 0:
Code:
create procedure MyProc @param1 int, @param2 int, @param3 bit=0
as
Back to your main question. I suggest you specify the @IsNewCust param with default value of NULL. In the sproc body you do an IF test for @IsNewCust IS NULL and execute without the IsNewCustomer filter
Code:
IF @IsNewCust IS NULL
BEGIN
SELECT * FROM TicketsWHERE (Tickets.SaleDate BETWEEN @StartDate AND @EndDate)
END
ELSE
BEGIN
SELECT * FROM TicketsWHERE (Tickets.SaleDate BETWEEN @StartDate AND @EndDate) AND (Tickets.IsNewCustomer = @IsNewCust)
END