flyinweb's blog

In most cases you'll want to create your database and it's schema as part of your applications first deployment. Depending on the scenario, you may create it on the client, or create it on the server, do the initial sync, then stream the file down to the client pre-populated.

Why would you create the database on the fly, rather than ship the initial database with your app?

While you could create the empty shell, and deploy it, you'll almost never want to start with a database that has data? Why? While in development, you'll have some set of data. Months later, when another user first installs your app that data may no longer be valid. Since most sync systems don't track deletes forever, you could wind up with data that is very stale, and now way to effectively update it.

介绍
现在 ASP.NET 2.0 提供了对成员资格（用户名/密码凭据存储）和角色管理服务的内置支持。由于所有这些服务都是提供程序驱动的（Provider），因此可以方便地用您自己的自定义实现替换。

This tutorial we will demonstrate how to access ASP.NET controls located in the LoggedInTemplate of a LoginView Control from the C# code behind class.

 C# code to convert a network in CIDR notation (72.20.10.0/24) to an IP address range

最近单位开发一个项目，其中需要用到自动升级功能。因为自动升级是一个比较常用的功能，可能会在很多程序中用到，于是，我就想写一个自动升级的组件，在应用程序中，只需要引用这个自动升级组件，并添加少量代码，即可实现自动升级功能。因为我们的程序中可能包含多个exe或者dll文件，所以要支持多文件的更新。

we have checked the posted file of the FileUpload and pass it to the IsImageFile() method that returns a Boolean type for checking the actual type of the posted file. If the file contains image extension such as “jpg”, “gif”, “bmp” and “png” then it will return TRUE else it will return false.

private void StartUpLoad() 
{ 
    if (FileUpload1.HasFile) 
    { 
        HttpPostedFile postedFile = FileUpload1.PostedFile; 
        if (IsImageFile(postedFile)) 
        { 
            //Save image here 
        } 
        else 
        { 
            Response.Write("Invalid File, Cannot Upload!"); 
        } 
    } 
    else 
    { 
        Response.Write("Please select a File"); 
    } 
} 
 
protected bool IsImageFile(HttpPostedFile file) 
{ 
    bool isImage = false; 
    System.IO.FileStream fs = new System.IO.FileStream(file.FileName, System.IO.FileMode.Open, System.IO.FileAccess.Read); 
    System.IO.BinaryReader br = new System.IO.BinaryReader(fs); 
 
    string fileclass = ""; 
    byte buffer; 
    try 
    { 
        buffer = br.ReadByte(); 
        fileclass = buffer.ToString(); 
        buffer = br.ReadByte(); 
        fileclass += buffer.ToString(); 
    } 
    catch 
    { 
        return false; 
    } 
    finally 
    { 
        br.Close(); 
        fs.Close(); 
    } 
 
    /*extension lists with codes 
     *7173        gif 
     *255216      jpg 
     *13780       png 
     *6677        bmp 
     *239187      txt,aspx,asp,sql 
     *208207      xls.doc.ppt 
     *6063        xml 
     *6033        htm,html 
     *4742        js 
     *8075        xlsx,zip,pptx,mmap,zip 
     *8297        rar   
     *01          accdb,mdb 
     *7790        exe,dll           
     *64101       bat 
     */ 
 
    //only allow images    jpg       gif     bmp     png      
    String[] fileType = { "255216", "7173", "6677", "13780" }; 
    for (int i = 0; i < fileType.Length; i++) 
    { 
        if (fileclass == fileType[i]) 
        { 
            isImage = true; 
            break; 
        } 
    } 
    return isImage; 
} 

 .NET 3.5 发布功能强大的新控件(Winform&WebForm) —— Chart

前言

11月25号，Scott在博客上发布了基于.NET Framework 3.5 SP1的图表控件——Chart，可在WinForm和WebForm下使用！并同时提供了大量的示例...