Question

We would like to update data in a SQL Server 2012 database with a value obtained from
changing a value on an ASP.Net DetailsView. I Would would like to update the database using

• a strongly typed DataSet called DataSetParentsDetails
• a TableAdapter called ParentsDetailsTableAdapter
• a DataTable called ParentsDetails.

These were created with the DataSet Designer.

This is the code from the code-behind file used to figure out the amount we want to update into the database:

Protected Sub DetailsViewDetails_ItemCommand(sender As Object, e As System.Web.UI.WebControls.DetailsViewCommandEventArgs)
  Dim dcmAmountToAdjust As Decimal
  Dim StrSqlStatement As String

  Select Case e.CommandName
    Case "Add"
    Case "Edit"
      dcmOriginalRegistrationFee = GetValueFromLabelRegistrationFee()
    Case "Delete"
    Case "Update"
      dcmNewRegistrationFee = GetValueFromTextBoxRegistrationFee()
      dcmAmountToAdjust = dcmNewRegistrationFee - dcmOriginalRegistrationFee
      ' Update the tuition balance in the parent's data.
      '-------------------------------------------------
      StrSqlStatement =
        "Update Students " & _
        "Set RegistrationCode = RegistrationCode + @AmountToAdjust " & _
        "Where StudentID = @ID"
      ' Code to update the database goes here.
      '---------------------------------------
  End Select
End Sub

I’m sure that this was asked many times before but I can’t find a good example on how to use the query in: StrSqlStatement to update the database through the strongly typed DataSet.

Answer 1

First off you need a connection string, it’s good practise to store your connection strings in the web.config file:

<connectionStrings>
  <add name="MyConnectionString" connectionString="Data Source=putYourServerAndInstanceNameHere;Initial Catalog=putYourDatabaseNameHere;User ID=putYourSqlUsernameHere;Password=password" providerName="System.Data.SqlClient" />
</connectionStrings>

This is a direct child of the root <configuration> element. For more information about connection strings, visit http://www.connectionstrings.com.

Then you’ll need some imports in your code-behind, and you’ll need to add them as references to your project if you haven’t already got them in there:

Import System.Data
Import System.Data.SqlClient

Then we connect to the database and run our command, we use parameters because they’re more secure.

'build the connection object using the string from the web.config file
Using conn As New SqlConnection(ConfigurationManager.ConnectionStrings("MyConnectionString").ConnectionString)
  'build the command object specifying the command text and the connection to use, conn
  Using cmd As New SqlCommand("UPDATE Students SET RegistrationCode = RegistrationCode + @AmountToAdjust WHERE StudentID = @ID", conn)
    'add the parameters needed by the command
    cmd.Parameters.AddWithValue("@AmountToAdjust", amountToAdjust)
    cmd.Parameters.AddWithValue("@ID", studentID)
    'try to open the connection and execute the statement
    Try
      conn.Open()
      cmd.ExecuteNonQuery()
    Catch ex As Exception
      'handle the exception here
    End Try
  End Using
End Using

Note that there is no need to use conn.Close() here as the Using statement will take care of that for you (SqlConnection’s Dispose method closes the connection if it is still open).