Please see following methods.

    public static ProductsCollection GetDummyData(int? customerId, int? supplierId)
    {
        try
        {
            if (customerId != null && customerId > 0)
            {
                Filter.Add(Customres.CustomerId == customerId);
            }

            if (supplierId != null && supplierId > 0)
            {
                Filter.Add(Suppliers.SupplierId == supplierId);
            }

            ProductsCollection products = new ProductsCollection();

            products.FetchData(Filter);

            return products;
        }
        catch
        {
            throw;
        }
    }

    public static ProductsCollection GetDummyData(int? customerId)
    {
        return ProductsCollection GetDummyData(customerId, (int?)null);
    }

    public static ProductsCollection GetDummyData()
    {
        return ProductsCollection GetDummyData((int?)null);
    }

1- Please advice how can I make overloads for both CustomerId and SupplierId because only one overload can be created with GetDummyData(int? ). Should I add another argument to mention that first argument is CustomerId or SupplierId for example GetDummyData(int?, string). OR should I use enum as 2nd argument and mention that first argument is CustoemId or SupplierId.

2- Is this condition is correct or just checking > 0 is sufficient -> if (customerId != null && customerId > 0)

3- Using Try/catch like this is correct?

4- Passing (int?)null is correct or any other better approach.

Edit:

I have found some other posts like this and because I have no knowledge of Generics that is why I am facing this problem. Am I right? Following is the post.

http://stackoverflow.com/questions/422625/overloaded-method-calling-overloaded-method