Question

当前，我正在使用预填充数据库附带的android应用程序。预先填充的数据库位于assets文件夹中，并且在其首次运行时将其复制到设备数据文件夹中。

数据库名称为“ Events.db”，该预填充数据库中有3个表。它们是事件，USER_EVENTS和通知。 EVENTSTable有240条记录，NOTIFICATIONS表有1条记录，并且USER_EVENTS表为空。用户保存一些数据时，将填充USER_EVENTS空表。将来，当我想向活动表中添加更多行而不影响其他表数据时，我需要找到一种方法。仅用于更新EVENTS表，而不影响USER_EVENTS表中用户输入的数据。因此，我试图更改数据库版本号，并且当它更改时，onUpgrade方法将触发并尝试实现我想要的功能。但是我不知道该怎么做，反正有实现这种情况的方法吗？或任何带有示例的建议？

当前这些是我的SqliteopenHelper类中的方法。

public class DatabaseHelper extends SQLiteOpenHelper {

private static final String DB_PATH = "/data/data/com.calendar.shanu.calendar/databases/";

    private static final String DB_NAME = "Events.db";
    private static final int DB_VERSION = 1;
    private final Context myContext;
    public SQLiteDatabase db;

    public DatabaseHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
        this.myContext = context;
    }

    public void createDataBase() throws IOException {
        boolean dbExist = checkDataBase();
        if (dbExist) {
            this.getWritableDatabase();
        } else {
            this.getWritableDatabase();
            try {
                this.close();
                copyDataBase();
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
        }

    }

    private boolean checkDataBase() {
        SQLiteDatabase checkDB = null;
        try {
            String myPath = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(myPath, null,SQLiteDatabase.OPEN_READWRITE);
            //checkDB.setVersion(DB_VERSION);
        } catch (SQLiteException e) {
        }
        if (checkDB != null)
            checkDB.close();
        return checkDB != null ? true : false;
    }

    private void copyDataBase() throws IOException {

        InputStream myInput = myContext.getAssets().open(DB_NAME);
        String outFileName = DB_PATH + DB_NAME;
        OutputStream myOutput = new FileOutputStream(outFileName);
        byte[] buffer = new byte[2048];
        int length;
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }
        myOutput.flush();
        myOutput.close();
        myInput.close();

        //myDataBase.setVersion(DATABASE_VERSION);
    }

    public void opendb() throws SQLException {
        String myPath = DB_PATH + DB_NAME;
        db = SQLiteDatabase.openDatabase(myPath, null,SQLiteDatabase.OPEN_READWRITE);
        Log.d("Test", "Database version: " +db.getVersion());
    }

    @Override
    public synchronized void close() {
        if (db != null)
            db.close();
        super.close();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        if(newVersion > oldVersion){
            myContext.deleteDatabase(DB_NAME);
            try {
                copyDataBase();
                Log.d("CopyDB", "in onUpgrade. Old is: " + oldVersion + " New is: " + newVersion);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }


    }
public void closedb(){
        if (db!=null){
            db.close();
        }
    }

//Database Insert, Update, Delete methods are in the below
}

任何帮助将不胜感激。

Answer 1

反正有实现这种情况的方法吗？

是的，虽然可能并不理想，但原则上：-

使用不同的名称命名新数据库，然后将其复制到资产文件夹。
使用类似的帮助程序将其打开，然后将其从资产文件夹中复制，然后
继续并复制相应表中的行，并将其插入到先前/旧数据库的相应表中。

也许所有这些都是在增加版本号之后从 onUpgrade 启动的。

其他评论：-

请给我看一个简单的示例代码。我认为使用复制数据游标是一种好方法，但我不明白如何读取表格来自两个表。

这是一个完整的示例，包括资产的副本

这假定原始数据库名为 events.db ，并具有3个表，即 event_table1 （已填充）， event_table2 （也已填充）和 event_table3 为空。

填充了 event_table3 的新数据库称为 events_extra.db ，并已放置在资产文件夹中。

一个名为 ImportFromSecondaryDB 的类（不能使用SQliteOpenHelper的子类来打扰），将资产文件夹中的数据库复制为第二个数据库，同时打开两个数据库，并从第二个数据库中提取所有行（第三个表，然后将行插入到原始数据库中。最后，它从辅助数据库中删除所有行。

public class ImportFromSecondaryDB {
    public static final int IFSDB_COMPLETIONCODE_ALLREADYDONE = 1;
    public static final int IFSDB_COMPLETIONCODE_ERRORCOPYINGDBFROMASSET = 2;
    SQLiteDatabase mPrimaryDB;
    SQLiteDatabase mSecondaryDB;
    int mCompletionCode = 0;
    int stage = 0;

    ImportFromSecondaryDB(Context context, String primaryDBName, String secondaryDBName) {

        File primaryDBFile = new File(context.getDatabasePath(primaryDBName).getPath());
        File secondaryDBFile = new File(context.getDatabasePath(secondaryDBName).getPath());
        byte[] buffer = new byte[4096];

        if (!primaryDBFile.exists()) {
            throw new RuntimeException("Unable to Import as the Primary Database does not exist!");
        }
        if (secondaryDBFile.exists()) {
            mCompletionCode = IFSDB_COMPLETIONCODE_ALLREADYDONE;
            return;
        }

        InputStream is;
        OutputStream os;
        int length = 0;
        int copied = 0;

        try {
            is = context.getAssets().open(secondaryDBName);
            stage++;
            os = new FileOutputStream(secondaryDBFile);
            stage++;
            while ((length = is.read(buffer)) > 0) {
                copied = copied + length;
                os.write(buffer);
            }
            stage++;
            os.flush();
            stage++;
            os.close();
            stage++;
            is.close();
            stage++;
        } catch (IOException e) {
            e.printStackTrace();
            mCompletionCode = IFSDB_COMPLETIONCODE_ERRORCOPYINGDBFROMASSET;
            throw new RuntimeException(
                    "Error copying secondary database from Asset " + secondaryDBName +
                            " to " + secondaryDBFile.getPath() + " at stage " + String.valueOf(stage)
            );
        }
        mPrimaryDB = SQLiteDatabase.openDatabase(primaryDBFile.getPath(),null,SQLiteDatabase.OPEN_READWRITE);
        mSecondaryDB = SQLiteDatabase.openDatabase(secondaryDBFile.getPath(),null,SQLiteDatabase.OPEN_READWRITE);

        ContentValues cv = new ContentValues();
        Cursor csr = mSecondaryDB.query("event_table3",null,null,null,null,null,null);
        mPrimaryDB.beginTransaction();
        while (csr.moveToNext()) {
            cv.clear();
            cv.put("name",csr.getString(csr.getColumnIndex("name")));
            mPrimaryDB.insert("event_table3",null,cv);
        }
        mPrimaryDB.setTransactionSuccessful();
        mPrimaryDB.endTransaction();
        mSecondaryDB.delete("event_table3",null,null); //???????
        mPrimaryDB.close();
        mSecondaryDB.close();
    }

    public int getCompletionCode() {
        return this.mCompletionCode;
    }  
}

请注意，getCompletionCode可以用于确定是否存在尚未导致引发异常的问题（已完成）。
请注意，这还没有经过太多的测试，因此草率地整理了一下，因为它只是作为指南。

以下是用于从Activity调用以上代码的代码：-

public class MainActivity extends AppCompatActivity {


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

        dumpAllThreeTables(); // Dump Existing tables
        ImportFromSecondaryDB mIFSDB = new ImportFromSecondaryDB(this,"events.db","events_extra.db"); // Do the import
        dumpAllThreeTables(); // Dump the changed tables
    }

    private void dumpAllThreeTables() {

        SQLiteDatabase mainDB = SQLiteDatabase.openDatabase(this.getDatabasePath("events.db").getPath(),null,SQLiteDatabase.OPEN_READWRITE);
        Cursor csr = mainDB.query("event_table1",null,null,null,null,null,null);
        DatabaseUtils.dumpCursor(csr);
        csr = mainDB.query("event_table2",null,null,null,null,null,null);
        DatabaseUtils.dumpCursor(csr);
        csr = mainDB.query("event_table3",null,null,null,null,null,null);
        DatabaseUtils.dumpCursor(csr);
        csr.close();
        mainDB.close();
    }
}

第一组转储表（在event_table3中没有结尾）：-

12-12 10:43:38.766 2842-2842/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534c2808
12-12 10:43:38.770 2842-2842/? I/System.out: 0 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=1
12-12 10:43:38.770 2842-2842/? I/System.out:    mainname=A
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 1 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=2
12-12 10:43:38.770 2842-2842/? I/System.out:    mainname=B
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 2 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=3
12-12 10:43:38.770 2842-2842/? I/System.out:    mainname=C
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 3 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=4
12-12 10:43:38.770 2842-2842/? I/System.out:    mainname=D
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 4 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=5
12-12 10:43:38.770 2842-2842/? I/System.out:    mainname=E
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 5 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=6
12-12 10:43:38.770 2842-2842/? I/System.out:    mainname=F
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 6 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=7
12-12 10:43:38.770 2842-2842/? I/System.out:    mainname=G
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 7 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=8
12-12 10:43:38.770 2842-2842/? I/System.out:    mainname=H
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 8 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=9
12-12 10:43:38.770 2842-2842/? I/System.out:    mainname=I
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: <<<<<
12-12 10:43:38.770 2842-2842/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534af7a8
12-12 10:43:38.770 2842-2842/? I/System.out: 0 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=1
12-12 10:43:38.770 2842-2842/? I/System.out:    secondaryname=Horse
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 1 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=2
12-12 10:43:38.770 2842-2842/? I/System.out:    secondaryname=Cow
12-12 10:43:38.770 2842-2842/? I/System.out: }
12-12 10:43:38.770 2842-2842/? I/System.out: 2 {
12-12 10:43:38.770 2842-2842/? I/System.out:    id=3
12-12 10:43:38.774 2842-2842/? I/System.out:    secondaryname=Rabbit
12-12 10:43:38.774 2842-2842/? I/System.out: }
12-12 10:43:38.774 2842-2842/? I/System.out: 3 {
12-12 10:43:38.774 2842-2842/? I/System.out:    id=4
12-12 10:43:38.774 2842-2842/? I/System.out:    secondaryname=Hare
12-12 10:43:38.774 2842-2842/? I/System.out: }
12-12 10:43:38.774 2842-2842/? I/System.out: 4 {
12-12 10:43:38.774 2842-2842/? I/System.out:    id=5
12-12 10:43:38.774 2842-2842/? I/System.out:    secondaryname=Cat
12-12 10:43:38.774 2842-2842/? I/System.out: }
12-12 10:43:38.774 2842-2842/? I/System.out: 5 {
12-12 10:43:38.774 2842-2842/? I/System.out:    id=6
12-12 10:43:38.774 2842-2842/? I/System.out:    secondaryname=Dog
12-12 10:43:38.774 2842-2842/? I/System.out: }
12-12 10:43:38.774 2842-2842/? I/System.out: 6 {
12-12 10:43:38.774 2842-2842/? I/System.out:    id=7
12-12 10:43:38.774 2842-2842/? I/System.out:    secondaryname=Porcupine
12-12 10:43:38.774 2842-2842/? I/System.out: }
12-12 10:43:38.774 2842-2842/? I/System.out: 7 {
12-12 10:43:38.774 2842-2842/? I/System.out:    id=8
12-12 10:43:38.774 2842-2842/? I/System.out:    secondaryname=Elephant
12-12 10:43:38.774 2842-2842/? I/System.out: }
12-12 10:43:38.774 2842-2842/? I/System.out: 8 {
12-12 10:43:38.774 2842-2842/? I/System.out:    id=9
12-12 10:43:38.774 2842-2842/? I/System.out:    secondaryname=Sheep
12-12 10:43:38.774 2842-2842/? I/System.out: }
12-12 10:43:38.774 2842-2842/? I/System.out: 9 {
12-12 10:43:38.774 2842-2842/? I/System.out:    id=10
12-12 10:43:38.774 2842-2842/? I/System.out:    secondaryname=Goat
12-12 10:43:38.774 2842-2842/? I/System.out: }
12-12 10:43:38.774 2842-2842/? I/System.out: <<<<<
12-12 10:43:38.774 2842-2842/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534c6e1c
12-12 10:43:38.774 2842-2842/? I/System.out: <<<<<

第二组转储表（请参阅event_table3（最后一个转储）现在如何获取数据）：-

12-12 10:43:38.790 2842-2842/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534ae284
12-12 10:43:38.790 2842-2842/? I/System.out: 0 {
12-12 10:43:38.790 2842-2842/? I/System.out:    id=1
12-12 10:43:38.790 2842-2842/? I/System.out:    mainname=A
12-12 10:43:38.790 2842-2842/? I/System.out: }
12-12 10:43:38.790 2842-2842/? I/System.out: 1 {
12-12 10:43:38.790 2842-2842/? I/System.out:    id=2
12-12 10:43:38.790 2842-2842/? I/System.out:    mainname=B
12-12 10:43:38.790 2842-2842/? I/System.out: }
12-12 10:43:38.790 2842-2842/? I/System.out: 2 {
12-12 10:43:38.790 2842-2842/? I/System.out:    id=3
12-12 10:43:38.790 2842-2842/? I/System.out:    mainname=C
12-12 10:43:38.790 2842-2842/? I/System.out: }
12-12 10:43:38.790 2842-2842/? I/System.out: 3 {
12-12 10:43:38.790 2842-2842/? I/System.out:    id=4
12-12 10:43:38.790 2842-2842/? I/System.out:    mainname=D
12-12 10:43:38.790 2842-2842/? I/System.out: }
12-12 10:43:38.790 2842-2842/? I/System.out: 4 {
12-12 10:43:38.790 2842-2842/? I/System.out:    id=5
12-12 10:43:38.790 2842-2842/? I/System.out:    mainname=E
12-12 10:43:38.790 2842-2842/? I/System.out: }
12-12 10:43:38.790 2842-2842/? I/System.out: 5 {
12-12 10:43:38.790 2842-2842/? I/System.out:    id=6
12-12 10:43:38.790 2842-2842/? I/System.out:    mainname=F
12-12 10:43:38.790 2842-2842/? I/System.out: }
12-12 10:43:38.790 2842-2842/? I/System.out: 6 {
12-12 10:43:38.790 2842-2842/? I/System.out:    id=7
12-12 10:43:38.790 2842-2842/? I/System.out:    mainname=G
12-12 10:43:38.790 2842-2842/? I/System.out: }
12-12 10:43:38.790 2842-2842/? I/System.out: 7 {
12-12 10:43:38.790 2842-2842/? I/System.out:    id=8
12-12 10:43:38.790 2842-2842/? I/System.out:    mainname=H
12-12 10:43:38.790 2842-2842/? I/System.out: }
12-12 10:43:38.790 2842-2842/? I/System.out: 8 {
12-12 10:43:38.790 2842-2842/? I/System.out:    id=9
12-12 10:43:38.790 2842-2842/? I/System.out:    mainname=I
12-12 10:43:38.790 2842-2842/? I/System.out: }
12-12 10:43:38.790 2842-2842/? I/System.out: <<<<<
12-12 10:43:38.790 2842-2842/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534c44b4
12-12 10:43:38.794 2842-2842/? I/System.out: 0 {
12-12 10:43:38.794 2842-2842/? I/System.out:    id=1
12-12 10:43:38.794 2842-2842/? I/System.out:    secondaryname=Horse
12-12 10:43:38.794 2842-2842/? I/System.out: }
12-12 10:43:38.794 2842-2842/? I/System.out: 1 {
12-12 10:43:38.794 2842-2842/? I/System.out:    id=2
12-12 10:43:38.794 2842-2842/? I/System.out:    secondaryname=Cow
12-12 10:43:38.794 2842-2842/? I/System.out: }
12-12 10:43:38.794 2842-2842/? I/System.out: 2 {
12-12 10:43:38.794 2842-2842/? I/System.out:    id=3
12-12 10:43:38.794 2842-2842/? I/System.out:    secondaryname=Rabbit
12-12 10:43:38.794 2842-2842/? I/System.out: }
12-12 10:43:38.794 2842-2842/? I/System.out: 3 {
12-12 10:43:38.794 2842-2842/? I/System.out:    id=4
12-12 10:43:38.794 2842-2842/? I/System.out:    secondaryname=Hare
12-12 10:43:38.794 2842-2842/? I/System.out: }
12-12 10:43:38.794 2842-2842/? I/System.out: 4 {
12-12 10:43:38.794 2842-2842/? I/System.out:    id=5
12-12 10:43:38.794 2842-2842/? I/System.out:    secondaryname=Cat
12-12 10:43:38.794 2842-2842/? I/System.out: }
12-12 10:43:38.794 2842-2842/? I/System.out: 5 {
12-12 10:43:38.794 2842-2842/? I/System.out:    id=6
12-12 10:43:38.794 2842-2842/? I/System.out:    secondaryname=Dog
12-12 10:43:38.794 2842-2842/? I/System.out: }
12-12 10:43:38.794 2842-2842/? I/System.out: 6 {
12-12 10:43:38.794 2842-2842/? I/System.out:    id=7
12-12 10:43:38.798 2842-2842/? I/System.out:    secondaryname=Porcupine
12-12 10:43:38.798 2842-2842/? I/System.out: }
12-12 10:43:38.798 2842-2842/? I/System.out: 7 {
12-12 10:43:38.798 2842-2842/? I/System.out:    id=8
12-12 10:43:38.802 2842-2842/? I/System.out:    secondaryname=Elephant
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: 8 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=9
12-12 10:43:38.802 2842-2842/? I/System.out:    secondaryname=Sheep
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: 9 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=10
12-12 10:43:38.802 2842-2842/? I/System.out:    secondaryname=Goat
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: <<<<<
12-12 10:43:38.802 2842-2842/? I/System.out: >>>>> Dumping cursor android.database.sqlite.SQLiteCursor@534c48c4
12-12 10:43:38.802 2842-2842/? I/System.out: 0 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=1
12-12 10:43:38.802 2842-2842/? I/System.out:    name=Z
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: 1 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=2
12-12 10:43:38.802 2842-2842/? I/System.out:    name=X
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: 2 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=3
12-12 10:43:38.802 2842-2842/? I/System.out:    name=Y
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: 3 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=4
12-12 10:43:38.802 2842-2842/? I/System.out:    name=W
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: 4 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=5
12-12 10:43:38.802 2842-2842/? I/System.out:    name=U
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: 5 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=6
12-12 10:43:38.802 2842-2842/? I/System.out:    name=R
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: 6 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=7
12-12 10:43:38.802 2842-2842/? I/System.out:    name=S
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: 7 {
12-12 10:43:38.802 2842-2842/? I/System.out:    id=8
12-12 10:43:38.802 2842-2842/? I/System.out:    name=T
12-12 10:43:38.802 2842-2842/? I/System.out: }
12-12 10:43:38.802 2842-2842/? I/System.out: <<<<<

附加2-纳入onUpgrade

public class DatabaseHelper extends SQLiteOpenHelper {

    private static final String DB_PATH = "/data/data/com.calendar.shanu.calendar/databases/";

    private static final String DB_NAME = "events.db"; //<<<<<<<<<<< Changed for testing
    private static final int DB_VERSION = 2; //<<<<<<<<<< Changed for Testing
    private final Context myContext;
    public SQLiteDatabase db;

    public DatabaseHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
        this.myContext = context;
    }

    public void createDataBase() throws IOException {
        boolean dbExist = checkDataBase();
        if (dbExist) {
            this.getWritableDatabase();
        } else {
            this.getWritableDatabase();
            try {
                this.close();
                copyDataBase();
            } catch (IOException e) {
                throw new Error("Error copying database");
            }
        }
    }

    private boolean checkDataBase() {
        SQLiteDatabase checkDB = null;
        try {
            String myPath = DB_PATH + DB_NAME;
            checkDB = SQLiteDatabase.openDatabase(myPath, null,SQLiteDatabase.OPEN_READWRITE);
            //checkDB.setVersion(DB_VERSION);
        } catch (SQLiteException e) {
        }
        if (checkDB != null)
            checkDB.close();
        return checkDB != null ? true : false;
    }

    private void copyDataBase() throws IOException {

        InputStream myInput = myContext.getAssets().open(DB_NAME);
        String outFileName = DB_PATH + DB_NAME;
        OutputStream myOutput = new FileOutputStream(outFileName);
        byte[] buffer = new byte[2048];
        int length;
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }
        myOutput.flush();
        myOutput.close();
        myInput.close();

        //myDataBase.setVersion(DATABASE_VERSION);
    }

    public void opendb() throws SQLException {
        String myPath = DB_PATH + DB_NAME;
        db = SQLiteDatabase.openDatabase(myPath, null,SQLiteDatabase.OPEN_READWRITE);
        Log.d("Test", "Database version: " +db.getVersion());
    }

    @Override
    public synchronized void close() {
        if (db != null)
            db.close();
        super.close();
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        if(newVersion > oldVersion){
            importFromSecondaryDB(myContext,db,"events_extra.db"); //<<<<<<<<<<
        }
    }
    public void closedb(){
        if (db!=null){
            db.close();
        }
    }

    private int importFromSecondaryDB(Context context, SQLiteDatabase maindb, String secondaryDBName) {


        File primaryDBFile = new File(maindb.getPath());
        File secondaryDBFile = new File(context.getDatabasePath(secondaryDBName).getPath());
        byte[] buffer = new byte[4096];

        // Check that the main database exist, if not then throw a runtime exception
        if (!primaryDBFile.exists()) {
            throw new RuntimeException("Unable to Import as the Primary Database does not exist!");
        }
        // If the secondary database exists then it has already been copied and thus data has been loaded
        // so return (can check returned code for allready done)
        if (secondaryDBFile.exists()) {
            return 1;
        }

        //Prepare for file handling (copy)
        InputStream is;
        OutputStream os;
        int length;
        int copied = 0;

        try {
            is = context.getAssets().open(secondaryDBName); // Get the assets file
            os = new FileOutputStream(secondaryDBFile); // Get the file to be written to
            // Loop though the asset file in chunks reading it and then writing to output
            while ((length = is.read(buffer)) > 0) {
                copied = copied + length;
                os.write(buffer);
            }
            // Copy done so flush and close files
            os.flush();
            os.close();
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
            throw new RuntimeException(
                    "Error copying secondary database from Asset " + secondaryDBName +
                            " to " + secondaryDBFile.getPath()
            );
        }
        // Open the newly copied database
        SQLiteDatabase mSecondaryDB = SQLiteDatabase.openDatabase(secondaryDBFile.getPath(),null,SQLiteDatabase.OPEN_READWRITE);

        //Copy the rows from the secondary (new) database, from table event_table3 to the main database's  event_table3
        //<<<<<<<<<< Note will have to be tailored to suit. >>>>>>>>>>>
        ContentValues cv = new ContentValues();
        // Extract the tables 
        Cursor csr = mSecondaryDB.query("event_table3",null,null,null,null,null,null);
        // Do in a Transaction
        maindb.beginTransaction();
        // Loop through extracted rows
        while (csr.moveToNext()) {
            cv.clear();
            cv.put("name",csr.getString(csr.getColumnIndex("name")));
            maindb.insert("event_table3",null,cv);
        }
        // ALl done so commit and close the transaction
        maindb.setTransactionSuccessful();
        maindb.endTransaction();
        // OPTIONAL delete the rows from the secondary table as they have been applied
        mSecondaryDB.delete("event_table3",null,null); //???????
        // Finally close the secondary database as done with it (main stays open)
        mSecondaryDB.close();
        return 0;
    }
}

升级预填充数据库而不会丢失当前数据

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附加2-纳入onUpgrade