declare @t table (
[id] [bigint],
[Parentid] [bigint],
[Name] [nvarchar](50)
)

insert into @t

select 1 as [Id], Null [Parentid] , N'Категория1'[Name] union all
select 2 as [Id], 1 [Parentid] , N'Категория2'[Name] union all
select 3 as [Id], 2 [Parentid] , N'Категория3'[Name] union all
select 4 as [Id], 2 [Parentid] , N'Категория4'[Name] union all
select 5 as [Id], Null [Parentid] , N'Категория5'[Name] union all
select 6 as [Id], 5 [Parentid] , N'Категория6'[Name] 
select * from @t;