Assign weight based on hierarchical depth - sql

Question

Take a table with values like below with two columns. I want the output in such a way that the count should be based on the depth of the hierarchy. Eg. A has a dependency on B,D and B has a dependency on C (C has not dependency) and D has dependencies on B,E and E has dependency on C and hence the weight of A is 6.
A B
A D
B C
D B
D E
E C
A 6
B 1
C 0
D 4
E 1
How can I write a SQL server query to achieve this output.

Answer 1

I think does what you want:
with cte as (
select col1, col2
from t
union all
select cte.col1, t.col2
from cte join
t
on t.col1 = cte.col2
)
select col1, sum(w)
from (select cte.col1, col2, 1 as w
from cte
union all
select col2, null, 0
from t
) t
group by col1;
Here is a db<>fiddle.

Answer 2

You could use cte for this:
select
child=cast(child as varchar(10)),
parent=cast(parent as varchar(10))
into #dat
from (values
('A','B'),('A','D'),('B','C'),('D','B'),('D','E'),('E','C')
) x (child,parent)
;with cte
as (
select distinct
parent as node,
0 as level,
parent as chain,
isleaf = case when exists (select 1 from #dat dpy where dpy.child=dp.parent) then 1 else 0 end
from #dat dp
where not exists (select 1 from #dat dpx where dp.parent=dpx.child)
union all
select
dc.child,
c.level+1,
cast(c.chain+dc.child as varchar(10)),
isleaf = case when exists (select 1 from #dat dcx where dcx.parent=dc.child) then 1 else 0 end
from #dat dc
join cte c
on c.node=dc.parent
)
select
node, sum(level)
from cte
group by node
result:
node weight
A 8
B 1
C 0
D 4
E 1
result of just select * from cte gives you structure overview:
node level chain isleaf
C 0 C 0
B 1 CB 1
E 1 CE 1
D 2 CED 1
A 3 CEDA 0
A 2 CBA 0
D 2 CBD 1
A 3 CBDA 0