my program is not adding items to listbox and is freezing up - sql

Question

im trying to add a very large amount of items to list box and what i need it for is i'm using to add selected items to itextsharp table report im using filters in the table just to display either the sales person who handled the customer or the date at which the incident occurred (or Issue was reported with the product) my filter system is as follows i have 4 categories which is 4 listboxes customer name, customer code(named listBox1 i have not got around to changing it yet) species name, and the error type my filter is placed under the searchBtn_Click event my filter and item adding code is as follows:
Private Sub searchBtn_Click(sender As Object, e As EventArgs) Handles searchBtn.Click
For Each obj As contactObject In custList
For Each item As speciesObject In speciesList
'loadLists()
If Trim(fromDate.Value) < Trim(obj.eventDate) Then
If Trim(toDate.Value) > Trim(obj.eventDate) Then
If Trim(fromDate.Value) < Trim(item.compDate) Then
If Trim(toDate.Value) > Trim(item.compDate) Then
End If
If Not customerListBox.Items.Contains(obj.customerName) Then
customerListBox.Items.Add(obj.customerName)
End If
If Not ListBox1.Items.Contains(obj.customer) Then
ListBox1.Items.Add(obj.customer)
End If
If Not speciesListBox.Items.Contains(item.name) Then
If ListBox1.Items.Contains(item.customerCode) Then
speciesListBox.Items.Add(Trim(item.name).ToUpper)
End If
End If
If Not errorListBox.Items.Contains(obj.issue + " - " + obj.issueDescription) Then
errorListBox.Items.Add(Trim(obj.issue + " - " + obj.issueDescription).ToUpper)
End If
End If
End If
End If
Next
Next
countErrors()
End Sub
then i have the query which is set up to get the customer info from the database system
Dim SqlText As String = "SELECT DISTINCT QEE.[EventID] ,QEE.[EventDate] ,QEE.[Employee] ,QEE.[Communication] ,QEE.[OtherCommunication] ,QEE.[Issue] ,QEE.[IssueDescription] ,QEE.[IssueComments] ,QEE.[Resolution] ,QEE.[ResolutionComments] ,QEE.[SalesOrderNumber] ,QEE.[CustomerPO] ,QEE.[SOStatus] ,QEE.[Customer] ,QEE.[CustomerName] ,QEE.[SalesPersonName] ,QEE.[IsResolved] ,QEE.[IssueValue] ,QEE.[DateAndTimeAdded] ,DATEDIFF(day, SOR.ReqShipDate, QEE.[EventDate]) AS Elapsed, SOR.ReqShipDate FROM [QualityTracking].[dbo].[tblQualityEventEntry] QEE INNER JOIN SysproCompanyC.dbo.SorMaster SOR ON QEE.SalesOrderNumber = SOR.SalesOrder COLLATE Latin1_General_CI_AS ORDER BY EventDate ASC, CustomerName ASC, SalesOrderNumber ASC;"
I could not fit all code on here
if you could also just general things to help as well i am new to vb.net but for other information things i have tried :
*listbox.startUpdate/endUpdate
*changing querys
*changing the sorted property (Right now its set for false)
*the issue happens when i choose select all and then hit search the database is holding almost 2Mil items and i need to be able to get it to move once i get it work stop freezing i will be able to increase the speed i just cant figure out totally where the issue is i know the query could be better probably (if you have any suggestions please feel free i'm learning)
*but i also see alot of people having this issue with listbox as being kinda a broken down way of listing items
*i have tried researching it and people have said use something else i cant do that for listbox is committed

Answer 1

Assuming Windows Forms.
You program might not be responding because of too many records to add, and each time you add an item into the ListBox.Items collection, the UI is refreshed.
You may either SuspendLayout while adding the lines into your Listbox, and ResumeLayout afterwards.
Private Sub searchBtn_Click(ByVal sender As Object, ByVal e As EventArgs)
customerListBox.SuspendLayout();
// Place your code to populate the ListBox control here...
customerListBox.ResumeLayout();
End sub
This shall avoid a lot of refreshes from occuring while adding the items one by one and allow the application to lighten the add of items, then you resume the layout so that it refreshes the controls to display adequate information to the screen.
OR
You may use the ListBox.Items.AddRange() method along with List.ToArray().
Private Sub searchBtn_Click(ByVal sender As Object, ByVal e As EventArgs)
Dim custList As List(Of ConstactObject) = loadYourCustomers();
customerListBox.Items.AddRange(custList.ToArray());
Dim speciesList As List(Of SpeciesObject) = loadYourSpecies();
speciesListBox.Items.AddRange(speciesList.ToArray());
End sub
OR ELSE
I recommend using a DataGridView and setting its DataSource property to your list of objects.
So, in order to have the correct data, you'll have to:
Drop two DataGridView on your Form
Rename both DataGridView to a meaningful name (e.g. custListDataGridView, speciesListDataGridview)
Drop two BindingSource on your Form
Rename both BindingSource to a meaningful name (e.g. custListBindingSource, speciesListBindingSource)
In the designer, set the DataGridView.DataSource property to your respective BindingSource (e.g. custListDataGridview.DataSource = custListBindingsource, speciesListDataGridView.DataSource = speciesListBindingSource)
In the backing code, that is, in your searchBtn.Click event, you may set both your binding sources DataSource property
Private Sub searchBtn_Click(ByVal sender As Object, ByVal e As EventArgs)
Dim custList As IList(Of ContactObject) = loadYourContactObjects();
custListBindingSource.DataSource = custList;
Dim speciesList As IList(Of SpeciesObject) = loadYourSpeciesObject();
speciesListBindingSource.DataSource = speciesList;
End Sub
And your information data should be listed automatically without you having to manually add each record.