Windows 7数据库添加值

Question

我现在正在创建一个应用程序，允许用户从本地数据库中创建和检索数据。有一个名为LIKE的列，默认值为int 0。我有一个按钮，但是我是否可以按下这个按钮，那么int 0的默认值将变成1？每次按下它，它都会将一个添加到默认值int中。我怎么能这么做？

Answer 1

假设您的数据库上下文设置为我在注释中提到的教程，则按钮单击事件可以如下所示：

    private void IncrementLikes_Click(object sender, RoutedEventArgs e)
    {
        //where Likes is your ObservableCollection keeping data from database
        LikeItem oneAndOnly = Likes.First() as LikeItem;
        //you pulled one and only LikeItem object, now you increment the likes count
        oneAndOnly.LikesCount += 1;
        //and here you tell the database that the changes need to be saved.
        //This call can be delayed to the OnNavigatedFrom event,
        //  depending on your needs.
        LikeDB.SubmitChanges();
    }

下面是属于页面的.cs文件的一些支持代码：

    //your database context
    private YourDatabaseDataContext LikeDB;

    // Define an observable collection property that controls can bind to.
    private ObservableCollection<LikeItem> _likes;
    public ObservableCollection<LikeItem> Likes
    {
        get
        {
            return _likes;
        }
        set
        {
            if (_likes != value)
            {
                _likes = value;
                NotifyPropertyChanged("Likes");
            }
        }
    }

    // Constructor
    public MainPage()
    {
        InitializeComponent();
        LikeDB = new YourDatabaseDataContext(YourDatabaseDataContext.DBConnectionString);
        this.DataContext = this;
    }

    protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
    {
        // Define the query to gather all of the to-do items.
        var likesFromDB = from LikeItem like in LikeDB.Likes
                            select like;

        // Execute the query and place the results into a collection.
        Likes = new ObservableCollection<LikeItem>(likesFromDB);

        // Call the base method.
        base.OnNavigatedTo(e);
    }

只为一个值使用数据库可能太多了，因此您可能需要考虑其他替代方法，例如Windows 设置。