simple error

[PankajChandak]

i am trying to loop into the dataset .Here is the vb.net code and error could anybody solve this simple problem

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim cnConnection As OleDbConnection
Dim adAdapter As OleDbDataAdapter
Dim dataset1 As New DataSet()



Dim strConnection As String
Dim strSQL As String
strConnection = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\CAFE\Database\UserDatail.mdb;Persist Security Info=False"
strSQL = "select * from mydata"
cnConnection = New OleDbConnection(strConnection)
adAdapter = New OleDbDataAdapter(strSQL, cnConnection)
adAdapter.Fill(dataset1)
Dim rowfirstName As System.Data.DataRow
'here is the error
For Each rowfirstName In dataset1.Tables("mydata").Rows

Console.WriteLine(rowfirstName("Firstname"))
Next
'error

txtName.Text = dataset1.Tables(0).Rows(0).Item(0)


End Sub


An unhandled exception of type 'System.NullReferenceException' occurred in WindowsApplication1.exe

Additional information: Object reference not set to an instance of an object.


Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.

[khalik_ash]

well

use Try...
Catch
end try for correct and clear error message.... and use to string

Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load 
Dim cnConnection As OleDbConnection 
Dim adAdapter As OleDbDataAdapter 
Dim dataset1 As New DataSet() 



Dim strConnection As String 
Dim strSQL As String 
Try
strConnection = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\CAFE\Database\UserDatail.mdb;Persist Security Info=False" 

strSQL = "select * from mydata" 
cnConnection = New OleDbConnection(strConnection) 

adAdapter = New OleDbDataAdapter(strSQL, cnConnection) 
adAdapter.Fill(dataset1) 
Dim rowfirstName As System.Data.DataRow 
'here is the error 
For Each rowfirstName In dataset1.Tables("mydata").Rows 

Console.WriteLine(rowfirstName("Firstname").ToString) 
Next 
'error 

txtName.Text = dataset1.Tables(0).Rows(0).Item(0) 

catch ex as Exception
 msgbox ex.message
end try
End Sub

[Lunatic3]

Change the line

adAdapter.Fill(dataset1)

as follows:

adAdapter.Fill(dataset1, "mydata")