要实现从两个RecyclerView向数据库发送请求，并在第三个RecyclerView中接收数据，您可以按照以下步骤进行操作：

1. 创建一个数据库帮助类（DatabaseHelper），用于创建和管理数据库以及执行数据库操作。

public class DatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "your_database_name";
    private static final int DATABASE_VERSION = 1;

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // 创建数据库表
        String createTableQuery = "CREATE TABLE your_table_name (id INTEGER PRIMARY KEY, data TEXT)";
        db.execSQL(createTableQuery);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // 数据库升级逻辑
    }

    // 向数据库插入数据
    public void insertData(String data) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put("data", data);
        db.insert("your_table_name", null, values);
        db.close();
    }

    // 从数据库查询数据
    public List getData() {
        List dataList = new ArrayList<>();
        SQLiteDatabase db = this.getReadableDatabase();
        Cursor cursor = db.rawQuery("SELECT * FROM your_table_name", null);
        if (cursor.moveToFirst()) {
            do {
                String data = cursor.getString(cursor.getColumnIndex("data"));
                dataList.add(data);
            } while (cursor.moveToNext());
        }
        cursor.close();
        db.close();
        return dataList;
    }
}

2. 创建一个适配器类（RecyclerViewAdapter）用于处理RecyclerView的数据展示。

public class RecyclerViewAdapter extends RecyclerView.Adapter {
    List dataList;

    public RecyclerViewAdapter(List dataList) {
        this.dataList = dataList;
    }
    
    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_layout, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        String data = dataList.get(position);
        holder.textView.setText(data);
    }

    @Override
    public int getItemCount() {
        return dataList.size();
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {
        TextView textView;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            textView = itemView.findViewById(R.id.textView);
        }
    }
}

3. 在Activity或Fragment中使用RecyclerView和数据库帮助类。

public class MainActivity extends AppCompatActivity {
    RecyclerView recyclerView1, recyclerView2, recyclerView3;
    RecyclerViewAdapter adapter1, adapter2, adapter3;
    List data1, data2, data3;
    DatabaseHelper databaseHelper;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        recyclerView1 = findViewById(R.id.recyclerView1);
        recyclerView2 = findViewById(R.id.recyclerView2);
        recyclerView3 = findViewById(R.id.recyclerView3);

        data1 = new ArrayList<>();
        data2 = new ArrayList<>();
        data3 = new ArrayList<>();

        adapter1 = new RecyclerViewAdapter(data1);
        adapter2 = new RecyclerViewAdapter(data2);
        adapter3 = new RecyclerViewAdapter(data3);

        recyclerView1.setLayoutManager(new LinearLayoutManager(this));
        recyclerView1.setAdapter(adapter1);

        recyclerView2.setLayoutManager(new LinearLayoutManager(this));
        recyclerView2.setAdapter(adapter2);

        recyclerView3.setLayoutManager(new LinearLayoutManager(this));
        recyclerView3.setAdapter(adapter3);

        databaseHelper = new DatabaseHelper(this);

        // 向数据库插入数据
        databaseHelper.insertData("Data 1");
        databaseHelper.insertData("Data 2");
        databaseHelper.insertData("Data 3");

        // 从数据库查询数据并更新RecyclerView
        data1.clear();
        data1.addAll(databaseHelper.getData());
        adapter1.notifyDataSetChanged();

        data2.clear();
        data2.addAll(databaseHelper.getData());
        adapter2.notifyDataSetChanged();

        data3.clear();
        data3.addAll(databaseHelper.getData());
        adapter3.notifyDataSetChanged();
    }
}

请注意，上述代码仅为示例，您可能需要根据您的实际需求进行适当的修改。此外，还需要在布局文件中添加相应的RecyclerView和TextView控件，并创建相应的item布局文件。