我有一个问题，创建一个有2列的数据库。第一个中应该有一个名字，第二个中应该有一个数字。创建名称数据库没有问题，但是当我尝试添加第二列时，我得到错误消息“I/数据库(13531)：SQLITE已返回：错误代码=1，消息=没有这样的列：zahl”
我的代码在这里
首先是经理

package my.studienarbeit.bestimmung.database;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DatenbankManager extends SQLiteOpenHelper {

private static final String DB_NAME = "carbohydrates.db";
private static final int DB_VERSION = 1;

private static final String WEIGHT_CREATE = 
         "CREATE TABLE weight (" 
        + "_id INTEGER PRIMARY KEY AUTOINCREMENT, " 
        +   "name TEXT NOT NULL, " +
    //  +   "zahl INTEGER" +
        ")";

public DatenbankManager(Context context) {
    super(context, DB_NAME, null, DB_VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
    db.execSQL(WEIGHT_CREATE);

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    Log.w(DatenbankManager.class.getName(),
        "Upgrading database from version " + oldVersion + " to "
                + newVersion + ", which will destroy all old data");
    db.execSQL("DROP TABLE IF EXISTS SCANITEM");
    onCreate(db);
}

}

和我的数据库：

package my.studienarbeit.bestimmung.database;

import my.studienarbeit.bestimmung.R;
import android.app.ListActivity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;

public class Datenbanken extends ListActivity {

private SQLiteDatabase mDatenbank;
private DatenbankManager mHelper;
/*/ private static final String WEIGHT_SELECT_RAW = 
        "SELECT _id, name, zahl FROM weight" ; //*/
        
//*/
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.daten_datenbanken);
    mHelper = new DatenbankManager(this);
    mHelper.getWritableDatabase();
    
}

@Override
protected void onPause() {
    super.onPause();
    mDatenbank.close();
    Toast.makeText(this, 
                 getResources().getString(R.string.tx_daten_datenbanken_db_geschlossen), 
            Toast.LENGTH_SHORT).show();
}

@Override
protected void onResume() {
    super.onResume();
    mDatenbank = mHelper.getWritableDatabase();
    Toast.makeText(
            this, 
            getResources().getString(
                    R.string.tx_daten_datenbanken_db_geoeffnet
                    ), 
            Toast.LENGTH_SHORT)
    .show();
    ladeDaten();

}

private void ladeDaten() {
     // Cursor weightCursor = mDatenbank.rawQuery(WEIGHT_SELECT_RAW, null);
Cursor weightCursor = mDatenbank.query("weight",
            new String [] {
                    "_id",
                    "name",
                //  "zahl",
            },
            null, null, null, null, null                
        ); 

    startManagingCursor(weightCursor);  
    SimpleCursorAdapter weightAdapter =
            new SimpleCursorAdapter(this, 
                    android.R.layout.simple_list_item_2, 
                    weightCursor, 
                    new String [] {
                    "name", 
                //  "zahl"
                    }, 
                    new int[] {
                        android.R.id.text1
                    }
                    
            );

setListAdapter(weightAdapter);
}

public void onNavButtonClick(View view) {
    EditText et_c = 
            (EditText) findViewById(R.id.editText_name_c);
//  EditText et_w = 
    //      (EditText) findViewById(R.id.editText_weight_c);
    
    ContentValues werte = new ContentValues();
    werte.put("name", et_c.getText().toString());
//  werte.put("zahl", et_w.getText().toString());
    mDatenbank.insert("weight", null, werte);
    ladeDaten();
    et_c.setText("");
//  et_w.setText("");

对于调试功能，第2列当前处于非活动状态。