How to write a procedure for displying the data in a TREE or (PARENT and CHILD ) relationship , for ex: A is the main project id, for this project B,C,D are sub tasks(sub project id's) for B the sub tasks are e,f,g and for c is h ,i ,j and for d is k,l,m
now i need to display the o/p in a TREE fashion

pls help me ,
thanks in advance
surendra