Android : Should I always use transactions in android sqlite?

Here is a simple example:

public boolean containsId(Long userid) {
    SQLiteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery("select * from " + getTableName() + " where id = " + userid, null);
    boolean rows = cursor.getCount() > 0;
    db.close();
    return rows;
}

I thought sqlite automatically starts a transaction. My colleague said I must always start a transaction.

So what is the right pattern? Should I start a transaction if I read data from database? I am sure that no other thread will write at this time in this table.