How to concatenate columns without null value in sql

Question

Hi coders,

 

I have a table in which i need to concatenate columns but i dont want NULL value in it. Example:

 

ProductTable

 

 Customer_Number   Product1  Product2 Product3 Product3

        1                           NULL      X               Y            NULL   

        2                           NULL      A               B            NULL

        3                              V         NULL         H            NULL 

 

Now want i want is the data in concatenated manner for product only like this:

 

Customer_Number Product

      1                         X,Y

      2                         A,B

      3                         V, H

 

 I already try Coalease, Stuff, ISNULL, NULLIF but in all i m getting like below 

 

Customer_Number          Product

      1                            NULL,X,Y,NULL

      2                           NULL,A,B,NULL

      3                          V, NULL,H,NULL

 

This is the code i used: 

Select Customer_number, ISNULL(IFNULLIF(Product1,' ')+',','')+

ISNULL(IFNULLIF(Product2,' ')+',','')+ 

ISNULL(IFNULLIF(Product3,' ')+',','')+

ISNULL(IFNULLIF(Product4,' ')+',','')

 

As Product from productTable 

 

Any help will be appriciated !!!