Tree related problem

How to find the child and subchild of particular node in a tree in sql.

more data needed for intelligent answer..

my database is like this:
{
id
name
subject
body
root_id
parent_id
lft
rgt
depth
created_at
updated_at
}

now what I want to do for the given id is I want to find all its
children and sub children

I think this work

Tell me guys whether this is absolutely fine or not as I haven't
checked it for all cases: