Question

我正在编写一个简单的数据库应用程序，您可以使用2个编辑文本输入您的名称和标记，然后按按钮保存数据库并转到显示数据库结果的第二个活动。该数据库包含4列：id，name，mark，operations 其中“operations”列从ops获取其结果，其中我已将其输入放入程序中。

我在插入时尝试捕捉并显示一个对话框，通知我它是否成功。结果是成功但是移动到查看活动时应用程序强制关闭。这是我的数据库类代码

 public class DateBase {

public static final String KEY_ID = "id";
public static final String KEY_NAME = "user_name";
public static final String KEY_MARK = "user_mark";
public static final String KEY_OPERATION = "operation";

private static final String DATABASE_NAME = "Statistic";
private static final String DATABASE_TABLE = "user_interface";
private static final int DATABASE_VERSION = 1;

private DBInterface MyInterface;
private final Context MyContext;
private SQLiteDatabase MyDB;


private static class DBInterface extends SQLiteOpenHelper
{

    public DBInterface(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        // TODO Auto-generated constructor stub
    }

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

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
        db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE );
        onCreate(db);
    }

}

public DateBase(Context c)
{
    MyContext = c;
}

public DateBase open() throws SQLException
{
    MyInterface = new DBInterface(MyContext);
    MyDB = MyInterface.getWritableDatabase();
    return this;
}

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

public long InsertEntry(String name, String mark, String ops) {
    // TODO Auto-generated method stub
    ContentValues cv = new ContentValues();
    cv.put(KEY_NAME, name);
    cv.put(KEY_MARK, mark);
    cv.put(KEY_OPERATION, ops);
    return MyDB.insert(DATABASE_TABLE, null, cv);
    }

public String getData() {
    // TODO Auto-generated method stub
    String[] columns = new String[] { KEY_ID, KEY_NAME, KEY_MARK, KEY_OPERATION};
    Cursor c = MyDB.query(DATABASE_TABLE, columns, null, null, null, null, null);
    String result = "";

    int iRow = c.getColumnIndex(KEY_ID);
    int iName = c.getColumnIndex(KEY_NAME);
    int iMark = c.getColumnIndex(KEY_MARK);
    int iOperation = c.getColumnIndex(KEY_OPERATION);

    for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext())
    {
        result = result + c.getString(iRow) + " " + c.getString(iName) + " " + c.getString(iMark) + " " + c.getString(iOperation) + "\n";
    }


    return result;
}
  }

这是插入代码，同时单击按钮：

 public void onClick(View v) {
    // TODO Auto-generated method stub

    boolean diditwork = true;
    try {String name = ed1.getText().toString();
    String mark = ed2.getText().toString();
    String ops = "";
    for (int i = 0; i < ops.length(); i++)
    {
        switch (op[i]) // int[] op = new int[]{1,3};
        {
        case 1:
            ops = ops + "+ ";
            break;
        case 2:
            ops = ops + "- ";
            break;
        case 3:
            ops = ops + "* ";
            break;
        case 4:
            ops = ops + "/ ";
            break;
        }
    }

    DateBase entry = new DateBase(MainActivity.this);
    entry.open();
    entry.InsertEntry(name, mark, ops);
    entry.close();

    } catch (Exception e)
    {
        diditwork = false;
        String error = e.toString();
        Dialog d = new Dialog (this);
        d.setTitle("NO WAY!!");
        TextView tv = new TextView(this);
        tv.setText(error);
        d.setContentView(tv);
        d.show();
    } finally {
        if (diditwork)
        {
            Dialog d = new Dialog (this);
            d.setTitle("Heck YA!");
            TextView tv = new TextView(this);
            tv.setText("Success");
            d.setContentView(tv);
            d.show();
        }
    }

    Intent i = new Intent();
    i.setClass(MainActivity.this, DatabaseView.class);
    startActivity(i);
     }

最后这是我的数据代码：公共类DatabaseView扩展了Activity {

TextView tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.database_view);

    tv = (TextView) findViewById(R.id.textView1);

    DateBase info = new DateBase(this);
    info.open();
    String Data = info.getData();
    info.close();

    tv.setText(Data);
}

}

我在LogCAT上遇到的例外是：

  E/AndroidRuntime(490): FATAL EXCEPTION: main
  java.lang.RuntimeException: Unable to start activity   
  ComponentInfo{com.database/com.database.DatabaseView}:       
  android.database.sqlite.SQLiteException: no such column: user_mark: , while compiling: SELECT id, user_name, user_mark, operation FROM user_interface

我无法弄清问题在哪里。请帮帮我，抱歉我的英文不好

感谢您的时间和考虑。

Answer 1

可能是你之后添加了这个字段user_mark，所以系统仍在使用旧数据库尝试卸载应用程序并再次安装它，否则我认为一切都很到位

Answer 2

是的，代码中没有错误，Aashish告诉他们这个问题。所以请清除管理应用程序中的数据并再次运行。

SQLite Android无法弄清楚我哪里出错了

2 个答案: