@Override

    public void onCreate(SQLiteDatabase db) {

        String sql="create table user ( username varchar(20) not null , password varchar(60) not null , regtime DATETIME );";

        db.execSQL(sql);

    }

        DatabaseDemoHelper dbDatabaseDemoHelper = new DatabaseDemoHelper(getApplicationContext());

        SQLiteDatabase db = dbDatabaseDemoHelper.getWritableDatabase();

        db.execSQL("delete from user", new Object[] {});

        ContentValues vls = new ContentValues();

        vls.put("username", "zhangsan");

        vls.put("password", "123");

        vls.put("regtime", new Date().toString());

        db.insert("user", null, vls);  

        ContentValues vls2 = new ContentValues();

        vls2.put("username", "lisi");

        vls2.put("password", "567");

        vls2.put("regtime", new Date().toString());

        db.insert("user", null, vls2); 

        //new Date().toString()       Fri Nov 06 23:58:57 GMT+08:00 2015

        //new Date().toLocaleString() 2015年11月7日 上午12:01:42

        //new Date().toGMTString()    6 Nov 2015 16:00:02 GMT

        Cursor cursor = db.rawQuery("select * from user order by regtime desc ", new String[] {});

        while (cursor.moveToNext()) {

            String userName = cursor.getString(cursor.getColumnIndex("username"));

            String password = cursor.getString(cursor.getColumnIndex("password"));

            String regtime = cursor.getString(cursor.getColumnIndex("regtime"));

            int i = 8;

        }