删除android中重复的适配器或SQL语句

我有下面的代码，它从数据库中获取记录并将它们放在适配器中，然后将适配器传递给微调器。问题是我想删除重复的适配器，但不想删除表。代码如下：

          try {
            Spinner spn2 = (Spinner)this.findViewById(R.id.spn2);     
            baseDatos = openOrCreateDatabase(nombreBD, MODE_WORLD_WRITEABLE, null);                 
            Cursor cur5 = baseDatos.rawQuery("SELECT DISTINCT codigo AS _id, usuario FROM mensajeswatotal", null);  

            startManagingCursor(cur5);
            String[] from = new String[]{"usuario"};
            int[] to = new int[] { android.R.id.text1 };           
            SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(Vsms.this,android.R.layout.simple_spinner_item, cur5, from, to); 

            mAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

             spn2.setAdapter(mAdapter);                 

         } catch (Exception e) {
            Log.i(TAG, "Error al abrir o crear la base de datos" + e);
         }

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您可以尝试添加GROUP BY子句：

从usuario的MensAjeswattal组中选择不同的codigo作为_id，usuario