SQLiteException：无法从版本1升级只读数据库2 [英] SQLiteException: Can't upgrade read-only database from version 1 to 2

问题描述

在我的数据库的第一个版本，我有三排。下面的方法是在扩展 SQLiteOpenHelper 。

一类

  @覆盖
公共无效的onCreate（SQLiteDatabase数据库）{
    database.execSQL（CREATE TABLE+ DATABASENAME +（Name文本，纬度REAL，经度REAL）;）;
}
 

现在，我已经改变了版本号从1到2，并增加了一个新行：

  @覆盖
公共无效的onCreate（SQLiteDatabase数据库）{
    database.execSQL（CREATE TABLE+ DATABASENAME +（Name文本，纬度REAL，经度REAL，国家TEXT）;）;
}
 

我不在乎旧数据库丢失，所以我用这个上升级：

  @覆盖
公共无效onUpgrade（SQLiteDatabase分贝，INT ARG1，ARG2 INT）{
    db.delete（DATABASENAME，NULL，NULL）;
    的onCreate（DB）;
}
 

现在，当我调用该方法 getReadableDatabase（），应用程序崩溃，与logcat的误差

  

产生的原因：android.database.sqlite.SQLiteException：无法升级   只读从版本1数据库到2：   /data/data/com.myapp.app/databases/mydb

我怎样才能prevent呢？

修改

满级：

 公共类StationsOpenHelper扩展SQLiteOpenHelper {

    私有静态最后弦乐DATABASENAME =站;
    私有静态最终诠释DATABASEVERSION = 2;

    公共StationsOpenHelper（上下文的背景下）{
        超（背景下，DATABASENAME，空，DATABASEVERSION）;
    }

    @覆盖
    公共无效的onCreate（SQLiteDatabase数据库）{
        database.execSQL（CREATE TABLE+ DATABASENAME +（Name文本，纬度REAL，经度REAL，国家TEXT）;）;
    }

    @覆盖
    公共无效onUpgrade（SQLiteDatabase分贝，INT ARG1，ARG2 INT）{
        db.delete（DATABASENAME，NULL，NULL）;
        的onCreate（DB）;
    }

    公众的ArrayList＆LT;站＆GT; getStations（）{
        Logger.log（试图读取数据库站）;
        ArrayList的＆LT;站＆GT;结果=新的ArrayList＆LT;站＆GT;（）;

        SQLiteDatabase数据库= getReadableDatabase（）;
        光标光标= database.rawQuery（SELECT * FROM+ DATABASENAME，NULL）;

        字符串名称，国家;
        双纬度，经度;
        站S;
        cursor.moveToFirst（）;
        而（！cursor.isAfterLast（））{
            S =新站（）;
            名= cursor.getString（0）;
            纬度= cursor.getDouble（1）;
            经度= cursor.getDouble（2）;
            国家= cursor.getString（3）;

            s.setName（名称）;
            s.setLatitude（LAT）;
            s.setLongitude（LON）;
            s.setCountry（国家）;

            result.add（多个）;

            cursor.moveToNext（）;
        }
        cursor.close（）;
        database.close（）;

        如果（result.isEmpty（））{
            Logger.log（从数据库中读取站失败）;
            结果= NULL;
        } 其他 {
            Logger.log（从数据库中读取站成功）;
        }

        返回结果;
    }

    公共无效storeStations（ArrayList中＆LT;站＆GT;站）{
        Logger.log（存储在数据库站）;
        ContentValues​​值=新ContentValues​​（）;
        SQLiteDatabase DB = getWritableDatabase（）;
        db.delete（DATABASENAME，NULL，NULL）;

        的for（int i = 0; I＆LT; stations.size（）;我++）{
            values​​.put（姓名，stations.get（ⅰ）.getName（））;
            values​​.put（纬度，stations.get（ⅰ）.getLatitude（））;
            values​​.put（经度，stations.get（ⅰ）.getLongitude（））;
            values​​.put（国家，stations.get（我）.getCountry（））;
            db.insert（DATABASENAME，空，价值观）;
        }

        db.close（）;
        Logger.log（在数据库中存储站成功）;
    }
}
 

解决方案

好吧，这里的解决方案，我建议，替换db.delete：

  db.execSQL（DROP TABLE IF EXISTS+ DATABASENAME）;
 

我有一种奇怪的感觉，将工作;）

In the first version of my database I had three rows. The following methods are in a class that extends SQLiteOpenHelper.

@Override
public void onCreate(SQLiteDatabase database) {
    database.execSQL("CREATE TABLE " + DATABASENAME + " (name TEXT, latitude REAL, longitude REAL);");
}

Now, I have changed the version number from 1 to 2, and added a new row:

@Override
public void onCreate(SQLiteDatabase database) {
    database.execSQL("CREATE TABLE " + DATABASENAME + " (name TEXT, latitude REAL, longitude REAL, country TEXT);");
}

I don't care that the old database is lost, so I use this on upgrade:

@Override
public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {
    db.delete(DATABASENAME, null, null);
    onCreate(db);
}

Now when I call the method getReadableDatabase(), the app crashes, with the logcat error

Caused by: android.database.sqlite.SQLiteException: Can't upgrade read-only database from version 1 to 2: /data/data/com.myapp.app/databases/mydb

How can I prevent this?

EDIT

The full class:

public class StationsOpenHelper extends SQLiteOpenHelper {

    private static final String DATABASENAME = "stations";
    private static final int DATABASEVERSION = 2;

    public StationsOpenHelper(Context context) {
        super(context, DATABASENAME, null, DATABASEVERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase database) {
        database.execSQL("CREATE TABLE " + DATABASENAME + " (name TEXT, latitude REAL, longitude REAL, country TEXT);");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) {
        db.delete(DATABASENAME, null, null);
        onCreate(db);
    }

    public ArrayList<Station> getStations() {
        Logger.log("Trying to read stations from database");
        ArrayList<Station> result = new ArrayList<Station>();

        SQLiteDatabase database = getReadableDatabase();
        Cursor cursor = database.rawQuery("SELECT * FROM " + DATABASENAME, null);

        String name, country;
        double lat, lon;
        Station s;
        cursor.moveToFirst();
        while (!cursor.isAfterLast()) {
            s = new Station();
            name = cursor.getString(0);
            lat = cursor.getDouble(1);
            lon = cursor.getDouble(2);
            country = cursor.getString(3);

            s.setName(name);
            s.setLatitude(lat);
            s.setLongitude(lon);
            s.setCountry(country);

            result.add(s);

            cursor.moveToNext();
        }
        cursor.close();
        database.close();

        if (result.isEmpty()) {
            Logger.log("Reading stations from database failed");
            result = null;
        } else {
            Logger.log("Reading stations from database succeeded");
        }

        return result;
    }

    public void storeStations(ArrayList<Station> stations) {
        Logger.log("Storing stations in database");
        ContentValues values = new ContentValues();
        SQLiteDatabase db = getWritableDatabase();
        db.delete(DATABASENAME, null, null);

        for (int i = 0; i < stations.size(); i++) {
            values.put("name", stations.get(i).getName());
            values.put("latitude", stations.get(i).getLatitude());
            values.put("longitude", stations.get(i).getLongitude());
            values.put("country", stations.get(i).getCountry());
            db.insert(DATABASENAME, null, values);
        }

        db.close();
        Logger.log("Storing stations in database succeeded");
    }
}

解决方案

Ok, here's the solution I propose, replace db.delete with:

db.execSQL("DROP TABLE IF EXISTS " + DATABASENAME);

I have a strange feeling that will work ;)

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