Name and version of the database you are using:mysql

I got a parent class with a java.util.List with a one-to-many relationship with its child class. when ever i delete a particular child object, and i try to load the List, the size of the list remain unchange, but i think the child object is store as null instead. its pretty troublesome this way because whenever i want to delete the child, i must also remove it from the parent list. does anyone know what have i miss out so this wouldn't happen? thanks :)