Desenvolvimento de banco de dados multitabela Android SQLite

public class Database extends SQLiteOpenHelper {

    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_NAME = "yourDatabaseName";

    //Declare a String for each Table name
    public static final String TABLE_NAME1 = "tableName1";
    public static final String TABLE_NAME2 = "tableName2";

    //Declare a SQL string for create each table
    private static final String CREATE_TABLE1 =
            "CREATE TABLE if not exists " + TABLE_NAME1 ..............";

    private static final String CREATE_TABLE2 =
            "CREATE TABLE if not exists " + TABLE_NAME2 .................";

    private static Database Singleton = null;
    private Context context;
    private static SQLiteDatabase Db;

    private Database(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);

        this.context = context;
    }

    public static synchronized Database getInstance(Context c){
        if(Singleton == null) {
            Singleton = new Database(c.getApplicationContext());
            Db = Singleton.getWritableDatabase();
        }
        return Singleton;
    }

    public SQLiteDatabase getDatabase() {

        return Db;
    }

     public synchronized void close() {

         if (Singleton != null && Db.isOpen()) Db.close();
     }


    @Override
    protected void finalize() throws Throwable  {

        try{
            close();
        }
        finally{
            super.finalize();
        }

    @Override
    public void onCreate(SQLiteDatabase db) {

        //Create Tables
        db.execSQL(CREATE_TABLE1);
        db.execSQL(CREATE_TABLE2);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

    }
}  

abstract class DatabaseTable {

    private SQLiteDatabase Db;
    private String TableName;

    public DatabaseTable(SQLiteDatabase db,String tableName) {

        this.TableName = tableName;
        this.Db = db;

    }

    public Cursor fetchAll() {

        Cursor cursor = Db.query(TableName, null, null, null, null, null, null);
        if (cursor != null) {
            cursor.moveToFirst();
        }
        return cursor;
    }

    public Cursor fetchAllOrderBy(String OrderField) {

        Cursor cursor = Db.query(TableName, null, null, null, null, null, OrderField);
        if (cursor != null) {
            cursor.moveToFirst();
        }
        return cursor;
    }

    public Cursor fetchById(long id) {

        Cursor cursor = Db.query(TableName, null, "_id = " + id, null, null, null, null);
        if (cursor != null) {
            cursor.moveToFirst();
        }
        return cursor;
    }

    public boolean deleteById(long id) {

        return Db.delete(TableName,"_id = " + id, null) > 0;
    }

    public boolean deleteAll() {

        return Db.delete(TableName,null, null) > 0;
    }

    public int getNumberRows() {

        return (int) DatabaseUtils.queryNumEntries(Db, TableName);
    }

}

public class TbTable1 extends DatabaseTable{

    //Declare string for each field name
    public static final String FIELD_ID = "_id";
    public static final String FIELD_FIELDNAME1 = "fieldName1";
    public static final String FIELD_FIELDNAME2 = "fieldName2";
    ..........
    ..........

    private SQLiteDatabase Db;

    //Get the table name from Database class
    private static final String TableName = Database.TABLE_NAME1;


    public TbTable1(SQLiteDatabase db) {

        super(db,TableName);
        this.Db = db;
    }

    // Below define all the methods you need to access this table

    public long insertRecord(String value1, String value2) {

        ContentValues initialValues = new ContentValues();
        initialValues.put(FIELD_FIELDNAME2, value1);
        initialValues.put(FIELD_FIELDNAME2, value2);
        return Db.insert(TableName, null, initialValues);
    }

    ..............
    ..............
}  

SQLiteDatabase Db = Database.getInstance(context).getDatabase();  
TbTable1 table1 = new TbTable1(Db);  
table1.insertRecord("Value1","Value2");
Cursor cursor = table1.fetchAll();

// do something with data

cursor.close();