Hey guys I know it had been discussed so much but I still don't get it working.

What I need is to filter a gridview by a few dropdown lists and the main idea is to "continue" filtering the gridview. I mean, when I select value from ddl1, then the ddl2 is filtered according to the selected value in ddl1 and so forth

Also called cascading dropdown list but I don't want to (can not) use Ajax Control Toolkit...

Any other solutions to that? Maybe the method

protected void DropDownList2_SelectedIndexChanged(...)

can do this but I don't know how to use it.


Please help Thanks in advance.

Do you mean to use only one datasource for all dropdown lists ?!
Otherwise I bind all the datasources in the code behind:

protected void Page_Load(object sender, EventArgs e)
        {

            if (!IsPostBack)
            {

                ddlProjectID.DataSource = sqlDataSourceProjectID;
                ddlProjectID.DataBind();
                

                if (!User.Identity.IsAuthenticated)
                {
                    Response.Redirect("~/ErrorPage.aspx");
                }

                ddlPad.DataSource = sqlDataSourcePad;
                ddlPad.DataBind();

                ddlStart_date.DataSource = SqlDataSourceStartDate;
                ddlStart_date.DataBind();

I tried the normal datasource line in the html code but same result...

i think you have data source with 2 tables :
table 1: dept
table 2: emp
FK: deptEmp_FK
add dataSource(DataSet,Linq,....) instance ds1
for Combo1 set data source dept table of ds1
for Combo2 set data source deptEmp_FK of ds1

No it's only one table and I'm using SQLDatasource for each dropdown list + the one for the gridview..
:?

ok you can go to the data source and create query

SELECT ID, Name, Dep FROM dbo.Emp
WHERE  Dep > @ParameterName

and press ok
set combo value member to the Dep
and in form on combo selectedIndexChanged

try
            {
                tableAdapterObj.NewQueryName(dataSetObj.Emp, new System.Nullable<int>(((int)(System.Convert.ChangeType(combobox1.selectedValue.ToString(), typeof(int))))));
            }
            catch (System.Exception ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);
            }

I don't really understand your point of using combo boxes rather than a normal dropdownlist.
I have another idea... in the data sources for each dropdown list, the sql SELECT command like this:

<asp:SqlDataSource ID="sqlDataSourcePad" runat="server"  
     ConnectionString="<%$ ConnectionStrings:LocalMySqlServer %>" 
     ProviderName="<%$ ConnectionStrings:LocalMySqlServer.ProviderName %>" 
     SelectCommand="SELECT DISTINCT user_field_2330 FROM task WHERE project__proj_short_name = @project">
        <SelectParameters>
            <asp:ControlParameter ControlID="ddlProjectID" Name="project" 
                PropertyName="SelectedValue" Type="String" />
        </SelectParameters>
    </asp:SqlDataSource>
asp:SqlDataSource ID="SqlDataSourceStartDate" runat="server" 
                ConnectionString="<%$ ConnectionStrings:LocalMySqlServer %>" 
                ProviderName="<%$ ConnectionStrings:LocalMySqlServer.ProviderName %>" 
                SelectCommand="SELECT DISTINCT start_date FROM task WHERE project__proj_short_name = @project AND pad_no=@pad">
     <SelectParameters>
            <asp:ControlParameter ControlID="ddlProjectID" Name="project" 
                PropertyName="SelectedValue" Type="String" />
            <asp:ControlParameter ControlID="ddlPad" Name="pad" 
                PropertyName="SelectedValue" Type="String" />
        </SelectParameters>
    </asp:SqlDataSource>

Do you think that this will work.. I don't get any data for start date if I use more than one select parameters :?

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