Question

I have a table with columns and data as follows:

Table1
ID  Name    PID
A1  Apple   P1
B1  Book    A1
B2  Brook   A1
C1  Cat     B1
C2  Cook    B1
C3  Car     B1
D1  Dog     B2
D2  Doll    B2
E1  Egg     C1

I want the results as follows:

ID  Name                    Depth
B1  Apple\Book              2
C1  Apple\Book\Cat          3
E1  Apple\Book\Cat\Egg      4
C2  Apple\Book\Cook         3
C3  Apple\Book\Car          3
B2  Apple\Brook             2
D1  Apple\Brook\Dog         3
D2  Apple\Brook\Doll        3

The relationship is that a row is a child of another row if PID of that row is equal to ID of the parent row.

Apple is the base. So the first statement would be something like:

Select ID, Name, 2 from Table1 where PID=(select ID from Table1 where Name='Apple');

My current solution is creating a lot of views and save all those similar statements like that to views and union them together. But I don’t want that. I want to finish that within 1 select statement.A

Answer 1

declare @Table1 table
(
  ID varchar(2),
  Name varchar(10),
  PID varchar(2)
)

insert into @Table1 values  
('A1',  'Apple',   'P1'),
('B1',  'Book',    'A1'),
('B2',  'Brook',   'A1'),
('C1',  'Cat',     'B1'),
('C2',  'Cook',    'B1'),
('C3',  'Car',     'B1'),
('D1',  'Dog',     'B2'),
('D2',  'Doll',    'B2'),
('E1',  'Egg',     'C1')

;with C as
(
  select T.ID,
         cast(T.Name as varchar(max)) as Name,
         1 as Depth
  from @Table1 as T
  where T.Name = 'Apple'
  union all
  select T.ID,
         cast(C.Name+'\'+T.Name as varchar(max)),
         C.Depth + 1
  from @Table1 as T
    inner join C
      on T.PID = C.ID
)
select C.ID,
       C.Name,
       C.Depth
from C
where C.Depth > 1
order by C.Name

Edit With out the Apple.

;with C as
(
  select T.ID,
         cast(T.Name as varchar(max)) as Name,
         1 as Depth
  from @Table1 as T
    inner join @Table1 as TP
      on T.PID = TP.ID
  where TP.Name = 'Apple'
  union all
  select T.ID,
         cast(C.Name+'\'+T.Name as varchar(max)),
         C.Depth + 1
  from @Table1 as T
    inner join C
      on T.PID = C.ID
)
select C.ID,
       C.Name,
       C.Depth
from C
order by C.Name