Slow form load when Databinding a Winform

[Vincent Dalton]

Hi all,

I am using ODP for .Net to build a multi-table dataset. The problem I am
running into is when I load the ZIP code table (42,741 records) into the
dataset and databind it to a combobox.

Try
' Fill the ZIP Code data table.
Dim da As New OracleDataAdapter, dr As OracleDataReader
Dim cmd As New OracleCommand("PACK_ZIP_CODES.ZIP_CODES", conORA)
With cmd
.CommandType = CommandType.StoredProcedure
.Parameters.Add(New OracleParameter("o_RESULT_SET",
OracleDbType.RefCursor, ParameterDirection.Output))
.Connection = conORA
End With
With da
.SelectCommand = cmd
.Fill(dsMulti, "ZIP_CODES")
.Fill(dsMulti, "E_ZIP_CODES")
End With
cmd.Dispose()
da.Dispose()
Catch ex As OracleException
Cursor.Current = Cursors.Default
MsgBox(ex.Message)
End Try

The form paints extremely slow. When I click on the tab that contains the
combobox, it also paints extremely slow. When I skip loading the ZIP Code
table into the dataset, the form loads quickly.

When I create a datareader based on the same ZIP Code table and load the
combobox, the form also paints very quick.

Dim cmdZIPS As New OracleCommand("PACK_ZIP_CODES.ZIP_CODES", conORA)
Dim drZIPs As OracleDataReader

With cmdZIPS
.CommandType = CommandType.StoredProcedure
.Parameters.Add(New OracleParameter("o_RESULT_SET", OracleDbType.RefCursor,
ParameterDirection.Output))
.Connection = conORA
End With
conORA.Open()
drZIPs = cmdZIPS.ExecuteReader(CommandBehavior.CloseConnection)
If drZIPs.HasRows Then
Do While drZIPs.Read()
cboH_ZIP_Code.Items.Add(drZIPs("ZIP_CODE"))
cboH_ZIP_Code.Tag = (drZIPs("CITY"))
cboE_ZIP_Code.Items.Add(drZIPs("ZIP_CODE"))
cboE_ZIP_Code.Tag = (drZIPs("CITY"))
Loop
End If

drZIPs.Close()

Unfortunately, the datareader can not be databound to the combobox. I need
to be able to:
1. Load the combobox quickly
2 Databind the combobox to the dataset

Does anybody out there have a solution?

Thanks in afvance.

Vince Dalton

 

[Greg Burns]

Unfortunately, the datareader can not be databound to the combobox. I need
to be able to:
1. Load the combobox quickly
2 Databind the combobox to the dataset

Does anybody out there have a solution?

Not sure exactly what you mean by not being able to databind using a
datareader. But here is some code that may help...

.....
cboH_ZIP_Code.BeginUpdate()
Do While dbDR.Read
cboH_ZIP_Code.Items.Add(New ListBoxItem(drZIPs("CITY").ToString,
drZIPs("ZIP_CODE").ToString))
Loop
cboH_ZIP_Code.EndUpdate()
.....


Public Class ListBoxItem

Private listItemData As Object
Private listItemText As String

' This is what is displayed in the ComboBox drop-down
Public Overrides Function ToString() As String
Return listItemText
End Function

Public Sub New(ByVal itemData As Object, ByVal itemText As String)

listItemData = itemData
listItemText = itemText
End Sub

Public ReadOnly Property Data() As Object
Get
Data = listItemData
End Get

End Property

Public ReadOnly Property Text() As String
Get
Text = listItemText
End Get

End Property

End Class

Greg

 

[Vincent Dalton]

Greg,

I have the combobox loading quickly now. I am having an issue with the
actual databound records.
To summarize, I have a table, CONTACTS, loaded into a dataset with 104
records. I have another table,
ZIP_CODES, with 40,000+ records. The ZIP Codes are loaded into a combobox,
which is databound. It takes forever to load the form, to move from record
to record, or update a record. If I remove the binding from the ZIP_CODE
table, the problem is gone. This defeats the purpose, though, as the record
is no longer bound. Do you know of a way I could speed up the form/dataset?

Thanks,

Vince