There is already an open DataReader associated with this Command which must be closed first

When your MVC 5 web application page tries to read the database using the Entity Framework in a loop you may get the following error message: InnerException: System.InvalidOperationException HResult=-2146233079 Message=There is already an open DataReader associated with this Command which must be closed first. Source=System.Data This usually happens when a cshtml page receives an IEnumerable<> […]

Windows web service authentication in IIS Express

When you develop a SOAP web service in Visual Studio 2013 the IDE uses IIS Express for testing. To set up Windows authentication in IIS Express follow the steps below: Create a Local Security Group on your computer Right click Computer and select Manage On the left side expand Local Users and Groups Right click […]

How to add tooltip to a Windows Form

In Windows Form applications the tooltip functionality is not built into the controls as in HTML objects. To add tooltip to your controls on Windows Forms Open the Windows Form in the designer Drag the ToolTip control from the Common Controls section of the Toolbox to the form. The ToolTip control will be placed at […]

How to add a DataGridView to a Windows Form

To display data in a DataGridView on a Windows Form Add a new form to the Win Form Application project Drag a BindingSource from the Toolbox to the form   The bindingSource object appears below the form   Rename the Binding Source Select the bindingSource1 object below the form Press F4 to display the Properties […]

DbArithmeticExpression arguments must have a numeric common type

The Microsoft Visual Studio 2013 Entity Framework database query does not support the subtraction of two dates to calculate TimeSpan. For example the following statement will throw a runtime error: site.VisitFrequencySec < ((TimeSpan)(dtNow – site.LastVisitDate)).TotalSeconds) To solve the problem create a computed database column to calculate the difference between the dates and use the computed […]

The underlying provider failed on Open

When you get the following error message in Microsoft Visual Studio 2013 check the inner exception. System.Data.Entity.Core.EntityException was unhandled   HResult=-2146233087   Message=The underlying provider failed on Open.   Source=EntityFramework The inner exception gives you detailed information on the real cause of the error. Most of the time the inner exception is the following: InnerException: […]

The Entity Framework provider … could not be loaded

When you create a new Microsoft Visual Studio 2013 project that uses the Entity Framework you may get the following error message: The Entity Framework provider type ‘System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer’ registered in the application config file for the ADO.NET provider with invariant name ‘System.Data.SqlClient’ could not be loaded. Make sure that the assembly-qualified name is used […]

Microsoft Azure – Storage – Part 5 – Delete blobs with a .NET application

In the prior article of the Microsoft Azure storage series we have downloaded a file (blob) from the container. In this part we will add a method to delete a blob in the Azure storage container. Delete a blob  in the storage container Add the DeleteBlob method to the Azure_Helper Open the Azure_Helper.cs file in […]

Microsoft Azure – Storage – Part 4 – Download files with a .NET application

In the third part of the Microsoft Azure Storage series we have extended our .NET application to list the contents of a container.  Today we will add a method to our application to download files from the storage container. Download blobs from the Microsoft Azure storage Create the DownloadFile method in the Azure Helper Open […]

Microsoft Azure – Storage – Part 3 – List the contents of the container with a .NET application

In the second part of the Azure Storage series we have developed a .Net application that can create a Microsoft Azure storage  container and upload files into it. Today we will extend the functionality of our application to list the files in the container. List the files in the container First let’s create a class […]