Question

I have the following table structure:

Table Days:          [_id,date,name]
                       ^
                       |
Table Events: [_id, day_id ,description]

The foreign key day_id is set to ON DELETE CASCADE

I want to “insert or update” the day 2. So I make:

ContentValues values= new ContentValues();
values.put("_id",2);
values.put("date,"...");
values.put("name","welcome");
mDb.replace("days",null,values);

The problem is that if the day_id=2 already exists (in my case is the most probably option) the DBengine deletes the table and inserts a new row so all the events associated to that day are also deleted.

This solution works but its very sub-optimal right?

    try {
        mDb.insertOrThrow("days", null, values);
    } catch (Exception e) {
        mDb.update("days", values, "_id=2", null);
    }

Whats the correct sollution for that problem

Answer 1

You should add your reference as below in order to allow SQLite to delete or update the referenced column automatically.

FOREIGN KEY [_id] REFERENCES [days] ON DELETE CASCADE ON UPDATE
CASCADE