Question

SQLite db example:

** I don’t create the db, it’s Android Bookmarks db, which I access using contentproviders.

** from what I understand after some searches, SQLite doesn’t support foreign key constraints but triggers are possible – http://www.sqlite.org/cvstrac/wiki?p=ForeignKeyTriggers

FOLDER column -> 0 = not a folder (false), 1 = a folder (true)

PARENT column -> holds the ID of its folder

ID  TITLE     FOLDER   PARENT
1   folder1      1        0
2   item1        0        1
3   item2        0        1
4   folder2      1        1
5   item1        0        4
6   item2        0        4
7   folder3      1        4
8   item1        0        7
9   item2        0        7

…and so on

On my Android app, I’m trying to recursively delete items from a SQLite db.
I have the ID of the first folder and I want to loop to find all it’s inner items (more folders and items).

For example – I have ID=1, so I can easily delete IDs 2 and 3 by requesting a query of all items their parent is ID=1, get items IDs and then delete.

The problem is I can’t figure out how to delete ID=4 and its inner items (item1, item2, and folder3) and then folder3 inner items.

Would love some help with this! been trying for hours :\

Thanks!

Answer 1

If in java then something like this I think, I think functions like findNextChildId should not be a problem:

 deleteFolderAndSub(int id){
        int childId = findNextChildId(id);
         //Let -1 be that there are no more children
        while (childId!=-1){
        if (checkIfFolder(childId)){
            deleteFolderAndSub(childId);
    //on exiting from above function folder should be empty so it can be deleted without problem
            deleteEmptyFolder(id);
        } else {
            deleteitem(id);
        }
//it should be while loop and we have to find another child inside the loop
        childId = findNextChildId(id)
      }
    }

findNextChildId(int parentId){
   Coursor yourCoursor;
  while(yourCoursor.moveToNext()){
    if (parentId==yourCoursor.getInt("PARENT")){
        yourCoursor.getInt("ID");
    }
  }
}