Question

Given a common parent/child table:

Table A
Column Id int
Column Parent_Id int
Column Description text

I would like to only get the nodes that does not have any child nodes.

1,null,"PARENT A"
2,null,"PARENT B",
3,null,"PARENT C", 
100,1,"CHILD A1",
101,1,"CHILD A2",
102,2,"CHILD B1"

So for my resultset I would like to only get:

Parent C (as it does not have any child elements), and child A1, B2, B1.

Answer 1

You don’t say what exactly you are querying with LINQ, but the general idea is

var leafNodes = nodes.Where(n => nodes.Count(n1 => n1.Parent_Id == n.Id) == 0);