Reading all rows in a column of a dataset

I have loaded the contents of an XML file into a dataset, and then into a datagrid.

But I am stuck with this (probably simple thing),

How do you read data from a specific field / column, or find out how many records / rows exist, in preferably the dataset. But if not possible, in the datagrid.

Thanks in advance for any help you can offer.

Code:

---

        Dim d As New DataSet()

        Try
            d.ReadXml("C:\test.xml")
            Me.DataGrid1.DataSource = d

        Catch exp As Exception
            MessageBox.Show(exp.Message.ToString, "Exception was caught", MessageBoxButtons.OK)
        End Try

        ds = d.Copy
        DataGrid1.DataSource = ds
        DataGrid1.Refresh()
        d.Dispose()

---

To find how many rows there are: ds.tables("mytable").rows.count
To read from a particular column: ds.tables("mytable").rows(r)(c)
where r is the row 0 based, and c is the column 0 based.

thank you

:) :( :o :D ;) :p :cool: :rolleyes: :mad: :eek: :confused:

When using it, I am getting the error:

An unhandled exception of type 'System.InvalidCastException' occurred in myClient.exe

Code:

---

      Dim a As Integer
        a = Me.ListBox1.SelectedIndex

        Me.lblFullName = ds.Tables("person").Rows(a)(0)    << ERROR at this line
        Me.lblFirstName = ds.Tables("person").Rows(a)("firstName")
        Me.lblDOB = ds.Tables("person").Rows(a)("birth")
        Me.lblFax = ds.Tables("person").Rows(a)("fax")
        Me.lblMobile = ds.Tables("person").Rows(a)("mobile")
        Me.lblMSN = ds.Tables("person").Rows(a)("msn")
        Me.lblSurname = ds.Tables("person").Rows(a)("surname")
        Me.lblTelNo = ds.Tables("person").Rows(a)("tel")
        Me.lblWebsite = ds.Tables("person").Rows(a)("website")
        Me.lblWork = ds.Tables("person").Rows(a)("work")
        Me.txtNotes = ds.Tables("person").Rows(a)("notes")

---

integer a, appears to be a valid number, that should exist, so anyone any ideas?

When no items are selected, listbox.selectedindex equals -1.Try to see if a=-1

solved it, forgot the .text

This will returns number of rows in database .

VB Code:

Public Function Nu_of_Rows(ByVal TableStr As String) As Integer
Dim SqlStr As String = "Select * FROM " & TableStr
Dim ds As New DataSet()
Dim adp As New OleDbDataAdapter(SqlStr, MyConnection)
adp.Fill(ds, TableStr)
Return ds.Tables(TableStr).Rows.Count
End Function