Question

我已尝试过此帖子中发布的解决方案： SQL Android Error: no such table

......无济于事。

我只是尝试打开并从我通过命令行创建的预构建SQLite数据库中获取所有行到我的应用程序。
它将文件保存为＆＃34; names.db＆＃34;。
我继续将它移动到我的主项目文件中的一个名为＆＃34; assets＆＃34; （＆＃34; C：\ ... \ AndroidStudioProjects \ MyProject的\应用\ SRC \主\资产\ names.db＆＃34）。

我一直在使用此堆栈解决方案作为模板，或多或少： https://stackoverflow.com/a/9109728/1438611

以下是我的堆栈跟踪抱怨的类的当前代码：

public class MainActivity extends Activity {
    private NamesDataSource dataSource;

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

        dataSource = new NamesDataSource(this);
        try {
            dataSource.open();
        }
        catch (SQLException se) {
            se.printStackTrace();
        }

        ListView lv = (ListView) findViewById(R.id.ListView);
        List<Names> values = dataSource.getAllNames();
        ArrayAdapter<Names> adapter = new ArrayAdapter<Names>(this, android.R.layout.simple_list_item_1, values);
        lv.setAdapter(adapter);
    }
}

// DBHelper class

public class MySQLiteHelper extends SQLiteOpenHelper {
    public static final String TABLE_NAMES = "names";
    public static final String COLUMN_ID = "_id";
    public static final String COLUMN_NAME = "name";

    private static final String DATABASE_NAME = "names.db";
    private static String DB_PATH = "";
    private static final int DATABASE_VERSION = 3;
    private static final String DATABASE_CREATE = "CREATE TABLE names (_id integer PRIMARY KEY, name text, phone text, email text);";
    private final Context mContext;
    private SQLiteDatabase mDataBase;

    public MySQLiteHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        DB_PATH = context.getApplicationInfo().dataDir + "/databases/";

        this.mContext = context;
    }

    public void createDataBase() throws IOException {
        //If database not exists copy it from the assets
        boolean mDataBaseExist = checkDataBase();
        if(!mDataBaseExist)
        {
            this.getReadableDatabase();
            try
            {
                //Copy the database from assets
                copyDataBase();
                Log.e("MySQLiteHelper", "createDatabase database created");
            }
            catch (IOException mIOException)
            {
                throw new Error("ErrorCopyingDataBase");
            }
        }
    }

    private boolean checkDataBase() {
        File dbFile = new File(DB_PATH + DATABASE_NAME);
        //Log.v("dbFile", dbFile + "   "+ dbFile.exists());
        return dbFile.exists();
    }

    private void copyDataBase() throws IOException
    {
        InputStream mInput = mContext.getAssets().open(DATABASE_NAME);
        String outFileName = DB_PATH + DATABASE_NAME;
        OutputStream mOutput = new FileOutputStream(outFileName);
        byte[] mBuffer = new byte[1024];
        int mLength;
        while ((mLength = mInput.read(mBuffer))>0)
        {
            mOutput.write(mBuffer, 0, mLength);
        }
        mOutput.flush();
        mOutput.close();
        mInput.close();
    }

    public boolean openDataBase() throws SQLException
    {
        String mPath = DB_PATH + DATABASE_NAME;
        mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
        return mDataBase != null;
    }

    @Override
    public void onCreate(SQLiteDatabase database) {
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }

    public Cursor fetchRows() {
        String query = "SELECT * FROM " + TABLE_NAMES;
        Cursor cursor = mDataBase.rawQuery(query, null);
        return cursor;
    }

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

// DAO / Adapter Class

public class NamesDataSource {
    private SQLiteDatabase db;
    private MySQLiteHelper dbHelper;
    private String[] allNames = {
            MySQLiteHelper.COLUMN_ID,
            MySQLiteHelper.COLUMN_NAME
    };

    public NamesDataSource(Context context) {
        dbHelper = new MySQLiteHelper(context);
    }

    public void open() throws SQLException {
        try {
            dbHelper.createDataBase();
        }
        catch (Exception ioe) {
            throw new Error("Unable to create database");
        }
        try {
            dbHelper.openDataBase();
        }
        catch(Exception se){
            se.printStackTrace();
        }
    }

    public void close() {
        dbHelper.close();
    }

    public List<Names> getAllNames() {
        List<Names> names = new ArrayList<>();

        Cursor cursor = dbHelper.fetchRows();

        cursor.moveToFirst();

        while(!cursor.isAfterLast()) {
            Names row = cursorToName(cursor);
            names.add(row);
            cursor.moveToNext();
        }

        cursor.close();
        return names;
    }

    private Names cursorToName(Cursor cursor) {
        Names name = new Names();
        name.setIds(cursor.getLong(0));
        name.setName(cursor.getString(1));
        name.setPhone(cursor.getString(2));
        name.setEmail(cursor.getString(3));

        return name;
    }
}

最后，错误报告：

android.database.sqlite.SQLiteException: no such table: names (code 1): , while compiling: SELECT * FROM names
            at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
            at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
            at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
            at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
            at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
            at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
            at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
            at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1316)
            at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1255)
            at com.example.user.myproject.MySQLiteHelper.fetchRows(MySQLiteHelper.java:96)
            at com.example.user.myproject.NamesDataSource.getAllNames(NamesDataSource.java:49)
            at com.example.user.myproject.MainActivity.onCreate(MainActivity.java:44)
            at android.app.Activity.performCreate(Activity.java:5990)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
            at android.app.ActivityThread.access$800(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5257)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)

非常感谢愿意看一眼的人欢呼声。

Answer 1

我没有看到你创建表格？创建它的代码在哪里？

您需要使用DATABASE_CREATE

onCreate()中的

尝试使用代码database.execSQL(DATABASE_CREATE);

并在onUpgrade()中添加db.execSQL("DROP TABLE IF EXISTS names");

请记住，它会缓存数据库，因此请尝试从头开始重新安装应用程序。

Answer 2

此路径错误：

DB_PATH = context.getApplicationInfo().dataDir + "/databases/";

它将返回

“/数据/数据/ com.example.user.myproject /数据库/数据库/”

但你只想要

“/数据/数据/ com.example.user.myproject /数据库/”

所以将其改为

DB_PATH = context.getApplicationInfo().dataDir;

或者，

DB_PATH = context.getDatabasePath(DATABASE_NAME).getPath();

我正在使用后者。

SQLite错误fetchRows（）上没有这样的表

2 个答案: