Question

在我的android活动中，我正在尝试从现有数据库中检索数据。我在资产中复制了数据库并试图访问它，但是在编译表列时显示错误，表示不存在这样的表。我也尝试了一些教程，但没有一个有用。我该怎么办？

以下是导致问题的代码。

DataBase Adapter类：

public static final String DATABASE_NAME="Wetrip";
public static final String DATABASE_TABLE="tour";
public static final int DATABASE_VERSION=1;
public final String TAG = "DBAdapter";

public static final String KEY_ID = "_id";
public static final String KEY_TOUR = "tour_name";
public static final String KEY_DAYS = "days";
public static final String KEY_NIGHTS = "nights";

final Context ctx;
DataBaseHelper dbhelper;
SQLiteDatabase sqlitedb;

   public ToursOpenHelper(Context context) {
       this.ctx = context;
       dbhelper = new DataBaseHelper(context); 
    }   
private static class DataBaseHelper extends SQLiteOpenHelper{
    DataBaseHelper(Context ctxt) {
        // TODO Auto-generated constructor stub
        super(ctxt, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub

    }

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

    }
}

//--open the DB
public ToursOpenHelper open() throws SQLException{
    sqlitedb = dbhelper.getWritableDatabase();
    return this;
}
public void close() {
    dbhelper.close();
}
public Cursor getAllData() {
    return sqlitedb.query(DATABASE_TABLE, new String[] {KEY_ID,KEY_TOUR,KEY_DAYS,KEY_NIGHTS}, null,null,null,null,null);
}

DatabaseActivity：

ToursOpenHelper toh = new ToursOpenHelper(this);
        try{
            String destPath = "/data/data/"+getPackageName()+"/databases";
            File f = new File(destPath);
            if(!f.exists()){
                f.mkdirs();
                f.createNewFile();

                //--copy db from assets
                CopyDB(getBaseContext().getAssets().open("wetrip"), new FileOutputStream(destPath+"/Wetrip"));
            }
        }
        catch(FileNotFoundException e){
            e.printStackTrace();
        }
        catch(IOException e){
            e.printStackTrace();
        }

        //--get all data
        toh.open();
        Cursor c = toh.getAllData();
        if(c.moveToFirst()){
            do{
                displayContact(c);
            }while(c.moveToNext());
        }
        toh.close();
    }

    public void CopyDB(InputStream in, OutputStream out) throws IOException {
        byte[] buffer = new byte[1024];
        int length;
        while((length = in.read(buffer)) >0){
            out.write(buffer,0,length);
        }
        in.close();
        out.close();
    }

    public void displayContact(Cursor cursor) {
        Toast.makeText(this, "id: "+cursor.getString(0)+"\n"+"Name: "+cursor.getString(2)+"\n"+"Days: "+cursor.getString(4)+"\n"+"Nights: "+cursor.getString(3)+"\n", Toast.LENGTH_LONG).show();
    }

Logcat输出：

08-10 14:19:41.423: E/AndroidRuntime(12764): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.travelplanner/com.example.travelplanner.DatabaseActivity}: android.database.sqlite.SQLiteException: no such table: tour: , while compiling: SELECT _id, tour_name, days, nights FROM tour
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.app.ActivityThread.access$600(ActivityThread.java:127)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.os.Handler.dispatchMessage(Handler.java:99)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.os.Looper.loop(Looper.java:137)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.app.ActivityThread.main(ActivityThread.java:4448)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at java.lang.reflect.Method.invokeNative(Native Method)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at java.lang.reflect.Method.invoke(Method.java:511)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at dalvik.system.NativeStart.main(Native Method)
08-10 14:19:41.423: E/AndroidRuntime(12764): Caused by: android.database.sqlite.SQLiteException: no such table: tour: , while compiling: SELECT _id, tour_name, days, nights FROM tour
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteCompiledSql.native_compile(Native Method)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteCompiledSql.<init>(SQLiteCompiledSql.java:68)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteProgram.compileSql(SQLiteProgram.java:143)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteProgram.compileAndbindAllArgs(SQLiteProgram.java:361)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:127)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:94)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:53)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1570)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1453)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1409)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1489)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at com.example.travelplanner.ToursOpenHelper.getAllData(ToursOpenHelper.java:59)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at com.example.travelplanner.DatabaseActivity.onCreate(DatabaseActivity.java:46)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.app.Activity.performCreate(Activity.java:4465)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
08-10 14:19:41.423: E/AndroidRuntime(12764):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
08-10 14:19:41.423: E/AndroidRuntime(12764):    ... 11 more

Answer 1

http://www.youtube.com/watch?v=A2NuI31Idls

这可能是有用的这是第111部分到124这么棒的教程我强烈建议你看它

Answer 2

您没有创建表格。您在Database Adapter类中使用以下代码。

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " KEY_TOUR + " TEXT NOT NULL, " + KEY_DAYS + " TEXT NOT NULL, " + KEY_NIGHTS + " TEXT NOT NULL);");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    if (oldVersion <= newVersion)
            return;
    db.execSQL("DROP TABLE IF EXISTS " + "CREATE TABLE " + DATABASE_TABLE + " (" KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " KEY_TOUR + " TEXT NOT NULL, " + KEY_DAYS + " TEXT NOT NULL, " + KEY_NIGHTS + " TEXT NOT NULL);");
    onCreate(db);

编辑：

您可以在数据库适配器中更改open方法

public ToursOpenHelper open() throws SQLException{
    sqLiteHelper = new SQLiteHelper(context, DATABASE_NAME, null, DATABASE_VERSION);
    sqlitedb = dbhelper.getWritableDatabase();
    return this;
}

如何处理“没有这样的表格例外”

2 个答案: