• How to Sort a Generic List

The key here is implementing the IComparable interface when creating your class (see link above for more information).  The IComparable interface has the CompareTo method that does the sorting. Once the interface is in place, you can use the sort method in the generic list: to sort your list (GenericList.Sort()).  Here is some sample code that implements the IComparable interface to an Ingredients Generic list.  To sort this list by IngredientID, instantiate the class (Dim objIngredientList as List(Of BEIngredientList = New List(Of BEIngredientList)}, popluate the list, and then excute the sort method objIngredientList.Sort().

  Public Class BEIngredientList 

   Implements IComparable(Of BEIngredientList)

#Region "Locals"

    Private _ingredientsID As Integer

    Private _ingredientName As String

    Private _ingredientCategoryID As Integer

#End Region

    Public Property IngredientID() As Integer

        Get

            Return _ingredientsID

        End Get

        Set(ByVal value As Integer)

            _ingredientsID = value

        End Set

    End Property

    Public Property IngredientName() As String

        Get

            Return _ingredientName

        End Get

        Set(ByVal value As String)

            _ingredientName = value

        End Set

    End Property

    Public Property IngredientCategoryID() As Integer

        Get

            Return _ingredientCategoryID

        End Get

        Set(ByVal value As Integer)

            _ingredientCategoryID = value

        End Set

    End Property

    Public Function CompareTo(ByVal other As BEIngredientList) As Integer Implements System.IComparable(Of BEIngredientList).CompareTo

        Return Me.IngredientID.CompareTo(other.IngredientID)

    End Function

End Class

 

• Computed Columns with Microsoft SQL 2005
  
  

  Select the table to which you want to add a computed column. From the Design screen, select the column name (in the example below we use a column called PreparedDryWeight).  Next, in the Column Properties screen expand the Computed Column Specification.  Enter the formula  into the (Formula) field as shown in the example below.
   
  (case when [PreparedMoisturePercentage]>(0) then [PreparedNetWeight]-[PreparedNetWeight]*([PreparedMoisturePercentage]*(0.01)) else (0) end)
  
  Note: You cannot use another computed column in the calculation.  Check ou this link The Power of SQL Case Statements by Scott Mitchell
  

• Refining a value from a Date data type field using the Value property .

  obj.DryingDate.Value.Date   -Get the Date as Date data type
  obj.DryingDate.Value.Year   -Get the Year as Integer data type
  
  

• Return a DataSet object type with Enterprise Library.  The key is the database.ExecuteDataSet(dbCommand) method.  See sample code below.
  
  

  Public Function GetDistinctBatchProductDesc(ByVal statusID As Integer, _
                                                  ByVal receivingLocationID As Integer) As DataSet
          Dim ret As New DataSet
          Dim db As Database = DatabaseFactory.CreateDatabase("SQLDataAccess")
          Dim sqlCommand As String = "Inventory.GetDistinctBatchProductDesc"
          Dim dbCommand As Common.DbCommand = db.GetStoredProcCommand(sqlCommand)
          db.AddInParameter(dbCommand, "StatusID", DbType.Int32, statusID)
          db.AddInParameter(dbCommand, "ReceivingLocationID", DbType.Int32, receivingLocationID)
          ret = db.ExecuteDataSet(dbCommand)
          Return ret
      End Function
  

• WPF Videos

• Preventing Users from Leaving Invalid Controls in Windows Forms.
  
  

  In a Validating event handler, you can prevent users from leaving the control containing the invalid entry until they clear or fix the error. If you look back to the code that assigned the event handler to the control, you will note that it wrapped the method in a CancelEventHandler. That provides the flexibility to add this line in the handling routine.

  e.Cancel = true; 
  
  ' Sample code that checks to make sure a textbox control contains text.
  
  
  Private Sub txtTypeCode_Validating(ByVal sender As System.Object, ByVal e As System.ComponentModel.CancelEventArgs) Handles txtTypeCode.Validating
          If Not Regex.IsMatch(txtTypeCode.Text, "\w") Then
   MessageBox.Show("Type Code CANNOT be blank", "Input Error", MessageBoxButtons.OK,           MessageBoxIcon.Error)
              ' Prevents users from leaving textbox until they fix it!
              e.Cancel = True
          Else
              txtTypeDesc.Focus()
          End If
  End Sub
   
  

  That line of code suppresses any events that would normally follow the Validating event.  To users, the code causes the cursor to remain stubbornly in the control; neither tabbing nor mousing will get it to budge until the user corrects the error.  For more information on the Validating event, see this MSDN article.
  
  

• How to make input parameters optional in T-SQL. Place an "=" sign after the datatype, and then assign a DEFAULT value.
  
  Create Procedure OptionalParametersDemo
     @floatTest      float=Null,
     @varcharTest varchar(10)=Null,
     @dateTest     datetime=Null,
     @intTest        int=Null
  As ...
  
  
• How to toggle a boolean field in VB.Net:  blnFlag = Not blnFlag
  

I was using the Cryptography portion Enterprise Library 3.1 for the encryption and decryption of data in my Windows application.  Part of the configuration process creates a key file (*.key) necessary for the encryption/decryption to work.

 It was all working fine until I tried to publish and deploy the application. The cryptography piece would not work when the application was deployed to another machine. Here is why. The algorithm that builds the key file uses local machine information to build the key.  When the key file is placed on another machine, the machine information is different; consequently the cryptography fails with the following error message: "Key not valid for use in specified state. \r\n" Source="System.Security" 

 How do you fix this problem?

1)      Create a password protected text version of the key file (for example, AppKey.txt). Use the Enterprise Library Application Configuration tool to create a text version of the key file (for example, AppKey.txt).

2)      When deploying your application, make sure you deploy the text version of your key file (AppKey.txt) and not the key file (AppKey.key).

3)      In your application, at start-up, add the following code I found on codeplex (see DevLingo entry July 17, 2007).  The code reads the text file (AppKey.txt) and recreates the key file (AppKey.key).  It then updates the app.config file, to point to the location of the new AppKey.key file.