gridview with multi select listbox - asp.net

Question

HiI have a list box that is bound to a table in a database. it produces a list of companies. The user will then come along and select multiple companies that they want to view information about, and then they hit a selet button which ill display the company information (e.g company name, company site, address e.t.c) in a gridview underneath. however the issue that i am having is that it only displays ONE of the multiple companies selected and its always the top one.
Can someone please shed some light on how i get all the companies to be displayed in the gridview?
i am programming in vb.net
please see source code below
<asp:ListBox ID="ListBox1" runat="server"
DataSourceID="SqlDataSource11" DataTextField="compName"
DataValueField="compDataID" SelectionMode="Multiple" AutoPostBack="True"></asp:ListBox>
<asp:SqlDataSource ID="SqlDataSource11" runat="server"
ConnectionString="<%$ ConnectionStrings:IWSRiskAssessmentConnectionString %>"
SelectCommand="SELECT [compDataID], [compName] FROM [tblCompany] WHERE ([compDataID] <> #compDataID) ORDER BY [compName]">
<SelectParameters>
<asp:ControlParameter ControlID="DropDownList1" Name="compDataID"
PropertyName="SelectedValue" Type="Int32" />
</SelectParameters>
</asp:SqlDataSource>
<asp:GridView
ID="GridView1" runat="server" AllowPaging="True" AutoGenerateColumns="False"
DataSourceID="SqlDataSource2">
<Columns>
<asp:BoundField DataField="compName" HeaderText="compName"
SortExpression="compName" />
<asp:BoundField DataField="Site Name" HeaderText="Site Name"
SortExpression="Site Name" />
<asp:BoundField DataField="Reference Number" HeaderText="Reference Number"
SortExpression="Reference Number" />
<asp:BoundField DataField="Asset" HeaderText="Asset" ReadOnly="True"
SortExpression="Asset" />
<asp:BoundField DataField="Location" HeaderText="Location"
SortExpression="Location" />
<asp:BoundField DataField="Block" HeaderText="Block" SortExpression="Block" />
<asp:BoundField DataField="Room" HeaderText="Room" SortExpression="Room" />
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="SqlDataSource2" runat="server"
ConnectionString="<%$ ConnectionStrings:IWSRiskAssessmentConnectionString %>"
SelectCommand="SELECT tblCompany.compName, tblSite.siteName AS [Site Name], tblSite.siteUPRN AS [Reference Number], tblIncMain.incAsset + ' ' + CAST(tblIncMain.incNumber AS varchar) AS Asset, tblIncMain.incLocation AS Location, tblIncMain.incBlock AS Block, tblIncMain.incRoom AS Room FROM tblIncMain INNER JOIN tblSite ON tblIncMain.incSite = tblSite.siteID INNER JOIN tblCompany ON tblSite.siteCompany = tblCompany.compDataID WHERE (tblIncMain.incActive = 1) AND (tblSite.siteActive = 1) AND (tblIncMain.incRemoved = 0) AND (tblCompany.compDataID = #compDataID) ORDER BY [Site Name], tblIncMain.incAsset, tblIncMain.incNumber">
<SelectParameters>
<asp:ControlParameter ControlID="ListBox1" Name="compDataID"
PropertyName="SelectedValue" />
</SelectParameters>
</asp:SqlDataSource>
this is the source code :-) please take a look and any help is greatly appreciated

Answer 1

May be DataBind code executes on every request or you are not collecting selected items from the listbox.
Sub page_load()
if Not IsPostBack Then
End If
End sub
and to iterate Listbox items,
For Each item in ListBox1.Items
if item.Selected then
End If
Next

Answer 2

Your data source is only selecting 1 record. The ListBox will return the first value when you use a multiple select ListBox as a ControlParameter.
(tblCompany.compDataID = #compDataID)
What you want to do is have something with an IN statement such as
(tblCompany.compDataID in #compData)
You may need to do something in the code behind.
<asp:ListBox ID="ListBox1" runat="server"
AutoPostBack="True"
DataTextField="compName"
DataSourceID="SqlDataSource11"
DataValueField="compDataID"
OnSelectedIndexChanged="ListBox1_SelectedIndexChanged"
SelectionMode="Multiple">
</asp:ListBox>
Code behind
protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e)
{
string s = string.Empty;
foreach (ListItem li in ListBox1.Items)
{
if (li.Selected == true)
s += li.Value + ",";
}
if (s != string.Empty)
{
s = s.Substring(0, s.Length - 2); // chop off trailing ,
SqlDataSource2.SelectParameters["compData"].DefaultValue = s;
}
}
NOTE this hasn't been tested but it is one option you can try. Basically you want a IN not a = for your select to get all results.

Answer 3

ok so i added 'in' to my sql statement, however it still only picked up one selection from the list box instead of multiple this is the sql statement:
SELECT tblCompany.compName, tblSite.siteName AS [Site Name], tblSite.siteUPRN AS [Reference Number], tblIncMain.incAsset + " " + CAST(tblIncMain.incNumber AS varchar) AS Asset, tblIncMain.incLocation AS Location, tblIncMain.incBlock AS Block, tblIncMain.incRoom AS Room FROM tblIncMain INNER JOIN tblSite ON tblIncMain.incSite = tblSite.siteID INNER JOIN tblCompany ON tblSite.siteCompany = tblCompany.compDataID WHERE (tblIncMain.incActive = 1) AND (tblSite.siteActive = 1) AND (tblIncMain.incRemoved = 0) AND tblCompany.compDataID in(#compDataID) ORDER BY [Site Name], tblIncMain.incAsset, tblIncMain.incNumber