Android开发—数据库应用—访问数据表（SQLite OpenHelper） —查询单条记录、修改

/* (程序头部注释开始)
* 程序的版权和版本声明部分
* Copyright (c) 2011, 烟台大学计算机学院学生
* All rights reserved.
* 文件名称：数据库应用—查询单条记录、修改
* 作者：雷恒鑫
* 完成日期： 2012 年 08 月 14 日
* 版本号： V1.0
* 对任务及求解方法的描述部分
* 输入描述：
* 问题描述：
* 程序输出：
* 程序头部的注释结束
*/

在“NotesDbAdapter”类中“查询单条记录”与“修改”的程序代码写好，程序如下：
[java]
//query single entry
public Cursor get(long rowId) throws SQLException {
      Cursor mCursor = db.query(true,
              DATABASE_TABLE,
              new String[] {KEY_ROWID, KEY_NOTE, KEY_CREATED},
              KEY_ROWID + "=" + rowId,
              null, null, null, null, null);
      if (mCursor != null) {
          mCursor.moveToFirst();
      }
      return mCursor;
}

//update
public boolean update(long rowId, String note) {
      ContentValues args = new ContentValues();
      args.put(KEY_NOTE, note);

      return db.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}

完整的“NotesDbAdapter.java”程序如下：

[java]
package com.demo.android.dummynote;

import java.sql.Date;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;

public class NotesDbAdapter {
    private static final String DATABASE_NAME = "notes.db";
    private static final int DATABASE_VERSION = 1;
    private static final String DATABASE_TABLE = "notes";
    private static final String DATABASE_CREATE = "creat table notes("
            + "_id INTEGER PRIMARY KEY," + "note TEXT," + "created INTEGER,"
            + "modified INTEGER" + ");";

    private static class DatabaseHelper extends SQLiteOpenHelper {
        public DatabaseHelper(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(DATABASE_CREATE);

        }

        @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);
        }
    }

    private Context mCtx = null;
    private DatabaseHelper dbHelper;
    private SQLiteDatabase db;

    public NotesDbAdapter(Context ctx) {
        this.mCtx = ctx;
    }

    public NotesDbAdapter open() throws SQLException {
        dbHelper = new DatabaseHelper(mCtx);
        db = dbHelper.getWritableDatabase();
        return this;
    }

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

    private static final String KEY_ROWID = "_id";
    static final String KEY_NOTE = "note";
    private static final String KEY_CREATED = "created";

    // get all entries
    public Cursor getall() {
        return db.query(DATABASE_TABLE, //Which table to Select
                new String[]{KEY_ROWID, KEY_NOTE,KEY_CREATED}, //Which columns to return
                null, //WHERE clause
                null, //WHERE arguments
                null, //GROUP BY clause
                null, //HAVING clause
                null);//Order-by clause

    }

    // add an entry
    public long create(String Note) {
        Date now = new Date();
        ContentValues args = new ContentValues();
        args.put(KEY_NOTE, Note);
        args.put(KEY_CREATED, now.getTime());

        return db.insert(DATABASE_TABLE, null, args);
    }

    //remove an entry
    public boolean delete(long rowID){
  &nbs

补充：移动开发 , Android ,