Execute non-query question with dataset results

Question

I have a fun project that involves VB.net winform app. This applications uses datasets for the forms. Three tables will be effected Shift_Log (SL), Problem_Log (PL) and Service_Request (SR). If the user changes the log dates on the (SL) so that the (PL) no longer agrees with the error time. I need to remove the foreign key from the (PL) and (SR) tables. I have not tested this yet. I have a couple of questions before I do.

1. What if there are no records to update in the second update (SR)sql command?

2. do I need to refresh the Dataset after this is executed.

    Public Function UPD_PL_Check(ByVal Shift_Key As String, ByVal SL_Begin As DateTime, SL_End As DateTime) As Integer
   
    ' Get rows from Laser Status Info
    Dim query As String = "SELECT Status_Key FROM [dbo].[Laser_Status_Info]  " &
                " WHERE [Shift_FKey] = " & Shift_Key &
                " AND [Err_time] NOT Between " & SL_Begin & " AND " & SL_End & ";"
   
    Dim dt As DataTable = New DataTable()
    Using conn As SqlConnection = New SqlConnection(My.Settings.LaserMaintLogConnectionString)
        conn.Open()
        Try
            Dim da As SqlDataAdapter = New SqlDataAdapter(query, conn)
            da.Fill(dt)
        Catch ex As Exception
            MessageBox.Show("Error occured! : " & ex.Message)
        Finally
            conn.Close()
        End Try
    End Using
   
    Dim rowsAffected As Integer = dt?.Rows.Count
   
    If rowsAffected = 0 Then Return rowsAffected
   
    ' Update the Problem log
    For Each i In dt?.Rows
        Using conn As SqlConnection = New SqlConnection(My.Settings.LaserMaintLogConnectionString)
            conn.Open()
            Dim Status_Key As String = dt.Rows(i)("Status_Key")
            Try
                Dim PL_query As String =
                 "UPDATE [dbo].[Laser_Status_Info] " &
                 "   SET [Shift_FKey] = '' " &
                 " WHERE [Status_Key] = '" & Status_Key & "';"
                Using Cmd As New SqlCommand(query, conn)
                    rowsAffected = Cmd.ExecuteNonQuery()
                End Using
   
            Catch ex As Exception
                MessageBox.Show("Error occured! : " & ex.Message)
            End Try
   
            ' Update Service request
            Try
                Dim PL_query As String =
                 "UPDATE [dbo].[Laser_Maint_Log] " &
                 "   SET [SR_Shift_Key] = '' " &
                 " WHERE [SR_Status_Key] = '" & Status_Key & "';"
                Using Cmd As New SqlCommand(query, conn)
                    rowsAffected = Cmd.ExecuteNonQuery()
                End Using
            Catch ex As Exception
                MessageBox.Show("Error occured! : " & ex.Message)
            End Try
            conn.Close()
        End Using
    Next
   
    Return rowsAffected
   

   End Function