How to Delete the parent node, and child nodes/leafs for a db/tbl in php

Hi. I've got a situation where I have a couple of tables. The relationship between the tables is one of parent/child. I'm trying to figure out the best approach to being able to delete the associated children in the child tbls, of a given parentID in the parentTBL... I've checked into various sites/articles on the 'net.. but i'm not sure how best to accomplish this... I'm using php as the interface language to the test tbls.. Any pointers/articles/test code (code/schema) would be helpful... Thanks