Cascade delete on many-to-many between same table

问题

I'm trying to create a many-to-many relation between the same table in SQL Server.

I have one table Object with columns ObjectId and Name.

The relation follows these rules:

a child can have many parents
a parent can have many children
ObjectA can be a child of ObjectB and ObjectB can be a child of ObjectA
but an object cannot be a direct child of itself

So I create a second table ObjectRelation with columns ParentId and ChildId and of course I want these relations to be deleted by cascade.

But when I try this in SQL Server I get the error

Introducing FOREIGN KEY constraint 'FK_ObjectRelation_Object1' on table 'tblADMembership' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.

In SQL Server Compact I get

The referential relationship will result in a cyclical reference that is not allowed.

I've done some research and I understand why I get these errors, but is there a way around this that will also work on SQL Server Compact (so no stored procedures)? Or is there a better way to model this relationship?

回答1:

I came across a similar problem myself....I ended up removing the foreign key. Cyclic deletion logic was pushed to Code.

回答2:

I had a similar problem with a treeview. This is a code to delete that was useful to me: (I save the id into the value property and I'm using a entity model framwork to delete) Maybe can help someone

private void removeRecursive(TreeNode parentToDelete)
    {
        foreach (TreeNode tn in parentToDelete.ChildNodes)
            removeRecursive(tn);

        long id = long.Parse(parentToDelete.Value);
        Category deleteCat = context.Categories.Single(x => x.Id ==id);
        context.Categories.DeleteObject(deleteCat);
    }

PD sorry about my english it's awful...

来源：https://stackoverflow.com/questions/13193935/cascade-delete-on-many-to-many-between-same-table

标签

sql

sql-server

sql-server-ce

Cascade