>Hello everyone
>PLs tel me how can i appconfig in my vb.net application for providing datasource path
>
>i want to design a form in which i wil input machine name like server\sqlexpress
>and database name when i click on save button i want save connection string in appconfigfile
>
>i m using vb.net and sqlexpress 2005
>
>how it can be done??

This (in C# but easy to convert) should write the connection string in the relevant section:

void WriteConnectionString(string name, string connectionstring)
        {
            System.Configuration.Configuration cfg = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
            cfg.ConnectionStrings.ConnectionStrings.Add(new ConnectionStringSettings(name, connectionstring));
            cfg.ConnectionStrings.SectionInformation.ForceSave = true;
            cfg.Save(ConfigurationSaveMode.Modified, true);
            ConfigurationManager.RefreshSection("connectionStrings");
        }

You can also use SQLDataSourceEnumerator to get a list of available SQL servers:

SqlDataSourceEnumerator sqlenum = SqlDataSourceEnumerator.Instance;
DataTable SQLList = sqlenum.GetDataSources();

Bear in mind that this doesn't write to the App.Config at runtime but to the [AppName].exe.Config file in the relevant bin folder.....