Can I group SQLite conditions in Android's Cursor query() method?

Question

I am trying to find a way to have threaded messaging in my app so I want to scan the database for messages that have the same two people as receivers and senders, for example: find all messages from Jack to Steve and from Steve to Jack and combine them in a threaded message view that has the messages sorted naturally by the primary key _id. At least that's how I think of doing it.

While trying to retrieve all the messages by a receiver, I have this method:

public ArrayList<Message> retrieveMessageFromReceiver(String email) {

        SQLiteDatabase db = this.getReadableDatabase();

        ArrayList<Message> messages = new ArrayList<Message>();
        Cursor cursor = db.query(TABLE_MESSAGES, new String[] { COLUMN_ID_M,
                COLUMN_SENDER_M, COLUMN_RECEIVER_M, COLUMN_CONTENT_M,
                COLUMN_TIMESTAMP_M, COLUMN_VISIBLE_TO_SENDER,
                COLUMN_VISIBLE_TO_RECEIVER, COLUMN_READ_STATUS },
                COLUMN_RECEIVER_M + "=?", new String[] { email }, null, null,
                null, null);

        if (cursor.moveToFirst()) {

            do {

                Message message = new Message(Integer.parseInt(cursor
                        .getString(0)), cursor.getString(1),
                        cursor.getString(2), cursor.getString(3),
                        cursor.getString(4), Integer.parseInt(cursor
                                .getString(5)), Integer.parseInt(cursor
                                .getString(6)), Integer.parseInt(cursor
                                .getString(7)));
            messages.add(message);

            } while (cursor.moveToNext());
        }

        return messages;
    }

Now, can I modify the query() statement to something like:

  Cursor cursor = db.query(TABLE_MESSAGES, new String[] { COLUMN_ID_M,
                COLUMN_SENDER_M, COLUMN_RECEIVER_M, COLUMN_CONTENT_M,
                COLUMN_TIMESTAMP_M, COLUMN_VISIBLE_TO_SENDER,
                COLUMN_VISIBLE_TO_RECEIVER, COLUMN_READ_STATUS }, "("
                + COLUMN_RECEIVER_M + "=?" + " AND " + COLUMN_SENDER_M + "=?"
                + ")" + " OR " + "(" + COLUMN_SENDER_M + "=?" + " AND "
                + COLUMN_RECEIVER_M + "=?" + ")", new String[] { email1,
                email2, email1, email2 }, null, null, null, null);

..so that the SQL syntax is "(receiver = ? AND sender = ?) OR (sender = ? AND receiver = ?)"? Obviously, I'd need to change the method arguments so that it accepts two arguments (email1 and email2).

I guess what I'm asking is: can the WHERE selectionArgs arguments correspond to as many "?"s in the selection string as I want? (four in this case). Does the grouping of the operators this way: " (? AND ?) OR (? AND ?) " have any effect on what I'm trying to achieve? Or am I going completely the wrong way about this?

Answer 1

This will work just fine.

Please note that parameter placeholders have another form that allows repeating the same parameter:

db.query(...,
         "(receiver = ?1 AND sender = ?2) OR (receiver = ?2 AND sender = ?1)",
         new String[] { email1, email2 },
         ...);