Any Detailed Source on Dataviews?

[dndaughtery]

I've searched all over th web on information on dataviews as well as bought 4 books which only breifly describe what a dataview is. I need a source that will allow me to get into the guts of dataviews. Does anyone know where I could find such info? Book? URL?

I have a project that requires that I be able to run a query on a Dataview or datatable and be able to count the rows.

[sevenhalo]

There's a member of DataView (DataView1.Count) that gives you the number of items.

Are you asking for something a little more specific? Can you give a more specified example of when you want to find out how many rows there are? Are you talking about finding out the number of rows effected when you run commands against DataViews and DataTables?

[dndaughtery]

Well, I could get by if I could bind a label to the dataview.count property. Is that possible? A sample would be deeply appreciated.

Dan

[sevenhalo]

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim strConn As String = "server=;Database=Northwind;user=;Password="
        Dim sqlConn As New SqlClient.SqlConnection(strConn)
        Dim strSQL As String = "SELECT * FROM Employees"
        Dim sqlCmd As New SqlClient.SqlCommand(strSQL, sqlConn)
 
        Dim adap As New SqlClient.SqlDataAdapter(sqlCmd)
        Dim ds As New DataSet
 
        Try
            'Query Northwind Employees
            sqlConn.Open()
            adap.Fill(ds, "Employees")
            Me.DataView1 = ds.Tables(0).DefaultView
            Me.Label1.text = DataView1.Count
        Catch ex As Exception
 
        Finally
            If sqlConn.State = ConnectionState.Open Then
                sqlConn.Close()
            End If
            sqlConn.Dispose()
            sqlCmd.Dispose()
            adap.Dispose()
        End Try
    End Sub

[dndaughtery]

thanks but I need to actually bind the DatView.count to the label because I'm going to be updating the datatable every minute. Will the code above reflect the updated datatable as well?

[sevenhalo]

No, but you can do this:

Private WithEvents dt As New DataTable
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim strConn As String = "server=;Database=Northwind;user=;Password="
        Dim sqlConn As New SqlClient.SqlConnection(strConn)
        Dim strSQL As String = "SELECT * FROM Employees"
        Dim sqlCmd As New SqlClient.SqlCommand(strSQL, sqlConn)
 
        Dim adap As New SqlClient.SqlDataAdapter(sqlCmd)
 
        Try
            'Query Northwind Employees
            sqlConn.Open()
            adap.Fill(dt)
            Me.DataView1 = dt.DefaultView
            Me.Label1.Text = Me.DataView1.Count  'set the initial
        Catch ex As Exception
 
        Finally
            If sqlConn.State = ConnectionState.Open Then
                sqlConn.Close()
            End If
            sqlConn.Dispose()
            sqlCmd.Dispose()
            adap.Dispose()
        End Try
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Me.DataView1.AddNew()
    End Sub
 
    Private Sub DataView1_ListChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ListChangedEventArgs) Handles DataView1.ListChanged
        Me.Label1.Text = Me.DataView1.Count 'refresh count
    End Sub

There is no "binding a label" to a dataview or datatable. You can associate events though.

**EDIT**
Changed the events (they were raising in a different order then I thought. This should work now that I tested it.)

[sevenhalo]

Bump

(Made a change to the example, need to grab your attention.)