android.database.sqlite.SQLiteException ： 无法将只读数据库从版本 0 升级到版本 1

Question

I are get android： android.database.sqlite.SQLiteException

无法将只读数据库从版本 0 升级到版本 1：/data/data/com.tuto.ListViewApp2_SQLite/databases/countryDB

当我运行模拟器时，它没有启动，它说"不幸的是 appName 已停止"，所以任何人都可以帮助我吗？

这是我的主要活动类：

package com.tuto.ListViewApp2_SQLite;
import com.tuto.ListViewApp2_SQLite.R;
import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.os.Bundle;
import android.provider.BaseColumns;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
public class MainActivity extends Activity {
    private CountryDB countryDatabase = null;
    private Cursor countries = null;
    private ListView lvCountries = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //Create the database helper
        CursorFactory factory = null;
        countryDatabase = new CountryDB(this, "countryDB", factory);
        String[] columnNames = {"Name", "Pop", "Area", BaseColumns._ID};
        lvCountries = (ListView) findViewById(R.id.lvCountries);
        int[] targetLayoutIDs = {R.id.textName, R.id.textPop, R.id.textArea};
        SQLiteDatabase db = countryDatabase.getReadableDatabase();
        countries = db.query("countries", columnNames, null, null, null, null, null);
        SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.country_item, 
                countries, columnNames, targetLayoutIDs, 0);    
        lvCountries.setAdapter(adapter);
    }
    @Override
    protected void onPause() {
        super.onPause();
        countryDatabase.close();
    }
}

这是我的SQLiteOpenHelper子类：

package com.tuto.ListViewApp2_SQLite;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
public class CountryDB extends SQLiteOpenHelper {
    private static final int DB_VERSION = 1;
    private static final String COUNTRY_TABLE_NAME = "countries";
    public CountryDB(Context context, String name, CursorFactory factory) {
        super(context, name, factory, DB_VERSION);
    }
    @Override
    public void onCreate(SQLiteDatabase dbCountries) {
        createTable(dbCountries);
    }
    @Override
    public void onUpgrade(SQLiteDatabase dbCountries, int oldVersion, int newVersion) {
        String dropSQL = "DROP TABLE IF EXISTS " + COUNTRY_TABLE_NAME +";";
        dbCountries.execSQL(dropSQL);
        createTable(dbCountries);
    }
    private void createTable(SQLiteDatabase dbCountries){
        String createSQL = "CREATE TABLE "+COUNTRY_TABLE_NAME+" ("+
                "_id INTEGER PRIMARY KEY AUTOINCREMENT, "+
                "Name TEXT, "+
                "Pop TEXT, "+
                "Area TEXT);";
        dbCountries.execSQL(createSQL);
        String insertSQL = "INSERT INTO " + COUNTRY_TABLE_NAME +
                " (Name, Pop, Area) " +
                "SELECT 'South Korea' AS NAME, '41,769,726' AS Pop, '1,068,296' AS Area"+
                " UNION SELECT 'Australia', '21,766,711', '2,967,893'" +
                " UNION SELECT 'India' , '1,189,172,906', '1,269,338',+" +
                " UNION SELECT 'United States', '313,232,044', '3,718,691';";
        dbCountries.execSQL(insertSQL);
    }
}

Answer 1

您的insertSQL未执行并失败。这就是您的数据库未升级的原因。插入查询在倒数第二个语句中有一个逗号和一个加号，这使得查询无效。

试试这个——

 String insertSQL = "INSERT INTO " + COUNTRY_TABLE_NAME +
                " (Name, Pop, Area) " +
                "SELECT 'South Korea' AS NAME, '41,769,726' AS Pop, '1,068,296' AS Area"+
                " UNION SELECT 'Australia', '21,766,711', '2,967,893'" +
                " UNION SELECT 'India' , '1,189,172,906', '1,269,338'" +
                " UNION SELECT 'United States', '313,232,044', '3,718,691';";

Answer 2

您的文件系统上已经有一个只读数据库。 其版本为 0。 您正在尝试将其升级到版本 1。 问题是它是只读的，所以你不能改变它。 最简单的解决方案是卸载并重新安装该应用程序，以摆脱旧应用程序。 或者检查旧数据库是否存在并先将其删除。 其中任何一个都会丢失其中的数据，但根据您的onUpgrade代码，无论如何都可以。