How to display corresponding values of combo box in text box?

@ Code Cruiser. Thanks I got you. But I  think I can not make changes to data it if I am reading through data reader. When the values  appear in the text boxes. I am supposed to edit, delete, or add new record to it. Thanks

Yes you can't do that with datareader. Given your requirements, I would use a DataGridView instead of combobox and textboxes.

This is how I am loading data in to combo box.

   Private Sub BuildDotCB()
        Dim dsDot As New DataSet
        Try
            DotCB.Items.Clear()
            Dim QueryString As String = "Select Distinct ID FROM tblSystemInformationEmployee "
            Dim drow As DataRow
            drow = Nothing
            dsId = New DataSet
            dsId= GetResultDataset(QueryString, ConnectionString)
            If IsValidDataset(dsDot) Then
                For Each drow In dsId.Tables(0).Rows
                    DotCB.Items.Add(drow(0).ToString())
                Next
            End If
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
    End Sub

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I wrote this data view function to manipulate the values as below.

  Private Sub ViewMode(ByVal GUID As String)
        Try

            Dim viewDs As New DataSet()
            Dim Query As String
            Query = "Select * from tblSystemEmployee Where UID = '" & GUID.Trim & "'"
            viewDs = GetResultDataset(Query, True)

            Dim dv As DataView = New DataView(viewDs.Tables(0))
            Dim Notify As String = String.Empty
            If dv.Count > 0 Then

                If Not IsDBNull(dv(0)("UID")) Then
                    txtHWGUID.Text = dv(0)("UID")
                Else
                    txtHWGUID.Text = String.Empty
                End If

              

                If Not IsDBNull(dv(0)("StreetName")) Then
                    txtHWStName.Text = dv(0)("StreetName")
                Else
                    txtHWStName.Text = String.Empty
                End If
            End If
        Catch ex As Exception
            MsgBox("No Values Found")
        End Try
    End Sub

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And called the above function on the selectionChangedEvent like this :

Private Sub IDCB_SelectionChanged(sender As System.Object, e As System.Windows.Controls.SelectionChangedEventArgs) Handles IDCB.SelectionChanged
        StreetCB.IsEnabled = False

        ViewMode(IDCB.SelectedItem.ToString)

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and When I select any value it show me "No Value found".

Am I missing any thing?

Please help me through this issue.
\
P.S. It is a WPf application.

Thanks!

Since you're getting "No values found", which is the message that is generated by getting an exception, it suggests that either you're getting an error from the query itself, or you're getting a record, but there's a problem in referencing it. Use the debugger to go through line by line. Which line is giving you the error? Offhand, my first thought is that you've specified one of the field names incorrectly (UID or StreetName), but you'd need to find which line is the problem to know for sure.