Usando COALESCE na visualização SQL

/* Set up sample data */
create table Customers (
    CustomerId int,
    CustomerName VARCHAR(100)
)

create table Orders (
    CustomerId int,
    OrderName VARCHAR(100)
)

insert into Customers
    (CustomerId, CustomerName)
    select 1, 'John' union all
    select 2, 'Marry'

insert into Orders
    (CustomerId, OrderName)
    select 1, 'New Hat' union all
    select 1, 'New Book' union all
    select 1, 'New Phone'
go

/* Create the view */       
create view OrderView as    
    select c.CustomerName, x.OrderNames
        from Customers c
            cross apply (select stuff((select ',' + OrderName from Orders o where o.CustomerId = c.CustomerId for xml path('')),1,1,'') as OrderNames) x
go

/* Demo the view */
select * from OrderView
go 

/* Clean up after demo */
drop view OrderView
drop table Customers
drop table Orders
go