Visual Basic

this is the sample of my code.. i know it sounds noob, but i just want to get it work.. =_=''

        Dim oraCommand As OracleCommand 
        Dim oraDr As OracleDataReader 
        Dim sqlCommand As SqlCommand 
        Dim sqlDr As SqlDataReader 
        Dim oraFieldCount, sqlFieldCount As Integer 
        Dim oraArr, sqlArr As New ArrayList 
        Dim strMissColPK, strMissColNotPK, strMissCol As String 
        Dim oraCount, sqlCount As Integer 
 
        Me.RichTextBox1.Clear() 
        If Me.chkData.Checked = False And Me.chkCol.Checked = False And Me.chkTable.Checked = False Then 
            Exit Sub 
        End If 
 
        For i As Integer = 0 To Me.ListBox1.SelectedItems.Count - 1 
            Try 
                oraCount = 0 
                sqlCount = 0 
                oraCon.Open() 
                oraCommand = New OracleCommand("select * from " & Me.ListBox1.SelectedItems(i).ToString, oraCon) 
                oraDr = oraCommand.ExecuteReader 
                oraDr.Read() 
                oraFieldCount = oraDr.FieldCount 
                oraArr.Clear() 
                For j As Integer = 0 To oraDr.FieldCount - 1 
                    oraArr.Add(oraDr.GetName(j).ToLower) 
                Next 
                oraDr.Close() 
                oraCommand = New OracleCommand("select count(*) from " & Me.ListBox1.SelectedItems(i).ToString, oraCon) 
                oraDr = oraCommand.ExecuteReader 
                If oraDr.Read Then 
                    oraCount = oraDr(0) 
                End If 
 
                sqlCOn.Open() 
                sqlCommand = New SqlCommand("select * from " & Me.ListBox1.SelectedItems(i).ToString, sqlCOn) 
                sqlDr = sqlCommand.ExecuteReader()  ## Here is where the system use about 2mb for each table. I have 400+ table ##
                sqlDr.Read() 
                sqlFieldCount = sqlDr.FieldCount 
                sqlArr.Clear() 
                For j As Integer = 0 To sqlDr.FieldCount - 1 
                    sqlArr.Add(sqlDr.GetName(j).ToLower) 
                Next 
                sqlDr.Close() 
                sqlCommand = New SqlCommand("select count(*) from " & Me.ListBox1.SelectedItems(i).ToString, sqlCOn) 
                sqlDr = sqlCommand.ExecuteReader() 
                If sqlDr.Read() Then 
                    sqlCount = sqlDr(0) 
                End If 
 
 
                If oraFieldCount > sqlFieldCount Then 
                    strMissCol = "" 
                    strMissColPK = "" 
                    strMissColNotPK = "" 
                    If Me.chkCol.Checked Then 
                        msgOut(" ================ Column not match." & Me.ListBox1.SelectedItems(i).ToString & ". Oracle Field: " & oraFieldCount & ", SQL Field: " & sqlFieldCount & ". " & " ================") 
 
                        For j As Integer = 0 To oraArr.Count - 1 
                            If sqlArr.IndexOf(oraArr(j)) = -1 Then 
                                Dim oraComm As New OracleCommand("select NULLABLE from USER_TAB_COLUMNS  where TABLE_NAME='" & Me.ListBox1.SelectedItems(i).ToString & "' AND COLUMN_NAME='" & oraArr(j).ToString.ToUpper & "'") 
                                Dim da As New OracleDataAdapter(oraComm.CommandText, oraCon.ConnectionString) 
                                Dim dt As New DataTable 
                                da.Fill(dt) 
 
                                If dt.Rows(0).Item(0).ToString = "N" Then 
                                    strMissColPK &= oraArr(j) & ", " 
                                Else 
                                    strMissColNotPK &= oraArr(j) & ", " 
                                End If 
                                strMissCol = oraArr(j) & ", " 
                                da = Nothing 
                                dt = Nothing 
                            End If 
                        Next 
 
                        msgOut("Oracle Records: " & oraCount & ",   SQL Records: " & sqlCount) 
                        msgOut("Additional Column in Oracle: " & strMissCol.TrimEnd(", ")) 
                        msgOut("    NotNULL : " & strMissColPK.TrimEnd(", ")) 
                        msgOut("    Normal : " & strMissColNotPK.TrimEnd(", ")) 
                        errorExist = True 
                    End If 
                ElseIf sqlFieldCount > oraFieldCount Then 
                    strMissCol = "" 
                    strMissColPK = "" 
                    strMissColNotPK = "" 
 
                    If Me.chkCol.Checked Then 
                        msgOut(" ================ Column not match." & Me.ListBox1.SelectedItems(i).ToString & ". Oracle Field: " & oraFieldCount & ", SQL Field: " & sqlFieldCount & ". " & " ================") 
                        For j As Integer = 0 To sqlArr.Count - 1 
                            If oraArr.IndexOf(sqlArr(j)) = -1 Then 
                                Dim sqlComm As New SqlCommand("select clmns.is_Nullable from sys.tables AS tbl INNER JOIN sys.all_columns AS clmns ON clmns.object_id=tbl.object_id  where tbl.name='" & Me.ListBox1.SelectedItems(i).ToString & "' and clmns.name='" & sqlArr(j) & "'", sqlCOn) 
                                Dim da As New SqlDataAdapter(sqlComm.CommandText, sqlCOn.ConnectionString) 
                                Dim dt As New DataTable 
                                da.Fill(dt) 
 
                                If dt.Rows(0).Item(0).ToString = "0" Then 
                                    strMissColPK &= sqlArr(j) & ", " 
                                Else 
                                    strMissColNotPK &= sqlArr(j) & ", " 
                                End If 
                                strMissCol &= sqlArr(j) & ", " 
                                da.Dispose() 
                                dt.Dispose() 
                            End If 
                        Next 
                        msgOut("Oracle Records: " & oraCount & ",   SQL Records: " & sqlCount) 
                        msgOut("Additional Column in SQL: " & strMissCol.TrimEnd(", ")) 
                        msgOut("    NotNULL : " & strMissColPK.TrimEnd(", ")) 
                        msgOut("    Normal : " & strMissColNotPK.TrimEnd(", ")) 
                        errorExist = True 
                    End If 
                Else 
                    If Me.chkData.Checked Then 
                        msgOut(Me.ListBox1.SelectedItems(i).ToString & ". Oracle Field: " & oraFieldCount & ", SQL Field: " & sqlFieldCount) 
                        If oraCount <> sqlCount Then 
                            msgOut("Not same ============>> Oracle Records: " & oraCount & ",   SQL Records: " & sqlCount) 
                        Else 
                            msgOut("Oracle Records: " & oraCount & ",   SQL Records: " & sqlCount) 
                        End If 
                    End If 
                End If 
 
 
                oraDr.Close() 
                sqlDr.Close() 
                CType(sqlDr, IDisposable).Dispose() 
                sqlCommand.Dispose() 
                oraDr = Nothing 
                sqlDr = Nothing 
                sqlCommand = Nothing 
                oraCon.Close() 
                sqlCOn.Close() 
                GC.Collect() 
 
            Catch ex As Exception 
                If oraCon.State = ConnectionState.Open Then 
                    oraCon.Close() 
                End If 
                If sqlCOn.State = ConnectionState.Open Then 
                    sqlCOn.Close() 
                End If 
                If Me.chkTable.Checked Then 
                    errorExist = True 
                    msgOut("================ Error:" & Me.ListBox1.SelectedItems(i).ToString & ". " & ex.Message & "================") 
                    msgOut("Oracle Records: " & oraCount & ",   SQL Records: " & sqlCount) 
                End If 
            End Try 
        Next 
        oraCon.Dispose() 
        sqlCOn.Dispose() 
        MsgBox("Check complete!")