sqlite更新数据不起效。很怪的问题，大家帮忙看看啊

public class UploadPicService extends Service {

	// / 上下文

	private Context context;

	/// 全局的应用

	private MyApplication mApplication;

	private Hashtable<String, JSONObject> updateDates;//保存正在上传的图片列表，如果返回了结果，则从中移出；

	private MediaDataDao daoservice;

	private TableData tabledata;

	private TableData mediaTable;

	@Override

	public IBinder onBind(Intent arg0) {

		return null;

	}



	@Override

	public void onCreate() {

		System.out.println("service create");

		context = getBaseContext();

		mApplication = MyApplication.getInstance();

		updateDates=new Hashtable<String, JSONObject>();

		daoservice = new MediaDataDao(context,MapSharePreferences.getUserDBDirectory(context));						

	}





	@Override

	public void onStart(Intent intent, int startId) {

		if (intent != null) {

			tabledata = daoservice.queryMaxByRid(mApplication.missionId,Constant.TABLE_ZHIFA_XCJC_ZN);

			mediaTable = daoservice.queryMaxByRid(tabledata.id,SystemConstant.MY_MEDIA_TABLENAME);

			new Thread(new Runnable() {

				@Override

				public void run() {

					try {

                                                  //图片上传等一系列操作后，无关数据库操作

  		                                Message msg=new Message();

						msg.what=1003;

						msg.obj=tempMediaTable;

						handler.sendMessage(msg);//更新数据库

											

			}).start();

		}

	}



	private Handler handler = new Handler() {

		@Override

		public void handleMessage(Message msg) {

			switch (msg.what) {

			case 1000:// 图片上传成功

				String errorMsg1 = (String) msg.obj;

				Toast.makeText(context, errorMsg1, Toast.LENGTH_LONG).show();

				break;

			case 1001:// 图片上传成功

				Toast.makeText(context, "图片上传成功！", Toast.LENGTH_LONG).show();

				break;

			case 1002:// 图片上传失败

				String errorMsg3 = (String) msg.obj;

				Toast.makeText(context, errorMsg3, Toast.LENGTH_LONG)

						.show();

			case 1003://更新数据

				TableData tempMediaTable=(TableData)msg.obj;

				System.out.println(tempMediaTable.body);

				daoservice.updateById(tempMediaTable, SystemConstant.MY_MEDIA_TABLENAME);

				TableData temp=daoservice.queryMaxByRid(tempMediaTable.rid,SystemConstant.MY_MEDIA_TABLENAME);

				System.out.println(temp.body);

				break;

			}

		}

	};

}

 public boolean updateById(TableData tableData, String tableName)

  {

    creatTable(tableName);

    try {

    	synchronized (this) {

    		db.beginTransaction();

    	      this.db.execSQL("update " + tableName + 

    	        " set rid = ?,head=?,body=?,location=? where id = ? ", 

    	        new String[] { tableData.rid, tableData.head, tableData.body, 

    	        tableData.location, tableData.id });

    	      db.setTransactionSuccessful();

    	      db.endTransaction();

		}

      return true;

    } catch (Exception e) {

    	e.printStackTrace();

    	db.endTransaction();

    }

    return false;

  }