How to create a summary row for a DataGrid in ASP.NET by using Visual Basic .NET
This step-by-step article describes how to create a summary row for a DataGrid control in ASP.NET by using Visual Basic .NET.
Original product version: Visual Basic .NET
Original KB number: 313154
In this article, you create a Visual Basic .NET project, add code to access the view named Sales Totals by Amount from the Northwind database, and then bind the Sales Totals by Amount view to the DataGrid. This sample uses the
ItemDataBound event of the DataGrid to total the SaleAmount field when you bind the data to the DataGrid. This sample also uses the footer of the DataGrid to display the summary or the totals.
This article refers to the Microsoft .NET Framework Class Library namespace
For a Microsoft Visual C# .NET version of this article, see 326339.
The following list outlines the recommended hardware, software, network infrastructure, and service packs that are required:
- Microsoft Windows
- Microsoft .NET Framework
- Microsoft Visual Studio .NET
- Microsoft Internet Information Services (IIS)
- Microsoft SQL Server 7.0 or later and the Northwind database
The Northwind database is included with SQL sServer 7.0 and later.
Create a Visual Basic .NET project and add the DataGrid
In this section, you create a Visual Basic .NET project, select a format for the DataGrid, and then set the DataGrid to display the footer. Because you use the footer to display the summary, it's important that you display the footer.
By default, the ShowFooter property is turned off.
Start Visual Studio .NET. The Visual Studio .NET IDE appears.
On the File menu, point to New, and then click Project.
In the New Project dialog box, click Visual Basic Projects under Project Types, and then click ASP.NET Web Application under Templates.
In the New Project dialog box, notice that the Name box is unavailable (it appears dimmed). The Location box contains the following text (or similar):
Change the location to
http://localhost/SummaryRow, and then click OK. A new project is created, which includes a Web Form that is named WebForm1.aspx.
In Solution Explorer, double-click WebForm1.aspx.
Drag a DataGrid control from the toolbox to the form.
Right-click the DataGrid control, and then click Auto Format. Click Colorful 1, and then click OK.
Right-click the DataGrid control, and then click Properties. In the Properties dialog box, change the value of the ShowFooter property to True.
Write code to access the database
In this section, you use the Sales Totals by Amount view that is located in the Northwind database to calculate the summary for the SaleAmount field. The Sales Totals by Amount view includes the Orders, the CompanyName, and the SaleAmount fields.
In the IDE, right-click the Web Form, and then click View Code.
In the code-behind window, add the following code to the top of the page:
Imports System.Data Imports System.Data.SqlClient
Add the following code in the class declaration section:
Private myTotal As System.Double 'This variable tracks the running total.
Replace the code in the
Page_Loadevent with the following code:
Private Sub Page_Load(ByVal sender As System.Object, _ ByVal e As System.EventArgs) Handles MyBase.Load 'Connect to the database, retrieve data, and then fill the data in the DataSet. Dim myConnection As New SqlConnection("server=(local)\netsdk;"Integrated Security=SSPI" & _ pwd=;database=northwind") Dim myDataAdapter As New SqlDataAdapter("SELECT top 15 [OrderID], [CompanyName], " & _ "[SaleAmount] FROM [Northwind].[dbo].[Sales Totals by Amount]", myConnection) Dim myDataSet As New DataSet() myDataAdapter.Fill(myDataSet) 'Set the DataSource for the DataGrid, and then bind the data. DataGrid1.DataSource = myDataSet DataGrid1.DataBind() End Sub
Modify the connection string as appropriate for your environment.
Use the ItemDataBound event
ItemDataBound event is raised after an item is data bound to the DataGrid control. This event gives you with the last opportunity to access the data item before it appears on the client. After this event is raised, the data item is null and is no longer available.
For each item that is data bound, you must check the
ItemType property. If
ItemType is of type
AlternatingItem, you receive the value from the last cell of the item, which contains the SaleAmount value. In this sample, you add this value to the running summary variable. When the
Footer, you receive the total from all of the rows. Therefore, you assign the value of the summary variable to the text value of the last cell.
This code uses formatting expressions to provide a uniform look for the SaleAmount data.
Add the following code after the
Private Sub DataGrid1_ItemDataBound(ByVal sender As Object, _ ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles DataGrid1.ItemDataBound Select Case e.Item.ItemType Case ListItemType.AlternatingItem, ListItemType.Item 'Calculate total for the field of each row and alternating row. myTotal += CDbl(e.Item.Cells(2).Text) 'Format the data, and then align the text of each cell to the right. e.Item.Cells(2).Text = Format(CDbl(e.Item.Cells(2).Text), "##,##0.00") e.Item.Cells(2).Attributes.Add("align", "right") Case ListItemType.Footer 'Use the footer to display the summary row. e.Item.Cells(1).Text = "Total Sales" e.Item.Cells(1).Attributes.Add("align", "left") e.Item.Cells(2).Attributes.Add("align", "right") e.Item.Cells(2).Text = myTotal.ToString("c") End Select End Sub
Build the project and test the code
- On the File menu, click Save All.
- On the Build menu, click Build Solution.
- In Solution Explorer, right-click the .aspx page, and then click View in Browser. The .aspx page appears in the browser, and the DataGrid displays the OrderID, the CompanyName, and the SaleAmount columns. Notice that the footer displays the total of the SaleAmount column.