Updating ASP controls on button click

[BlueAcolyte]

*Edit:* blah I'm an idiot. I forgot to add If Not IsPostBack to the loading of the drop list, so every time the button was pressed the page reloaded and reset the drop list. Mods can kill it...

Alright, so I'm kinda new to programming, working on a asp.net program linked to a database.

I have this drop list with different categories in it, and when a button is clicked, I want a gridview based on the item selected in the list.

Here's the code-behind (It's in VB)

    Protected Sub submit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles submit.Click
        BindGrid()
    End Sub

    Sub BindGrid()
        Dim conn As SqlConnection
        Dim connectionString As String = ConfigurationManager.ConnectionStrings("*****").ConnectionString
        Dim reader As SqlDataReader
        conn = New SqlConnection(connectionString)

        Dim comm As New SqlCommand("SELECT RTRIM([DocumentName]) AS [DocName] FROM [DocumentInfo] WHERE ([DepartID] = @DepartID)", conn)
        comm.Parameters.Add("@DepartID", System.Data.SqlDbType.Int)
        comm.Parameters("@DepartID").Value = DeptNameDropList.SelectedItem.Value

        conn.Open()
        reader = comm.ExecuteReader()
        GridView1.DataSource = reader
        GridView1.DataBind()
        reader.Close()
        conn.Close()
    End Sub

So hopefully you can see from the code that upon clicking the button, a gridview is populated with items based on the selected value of the drop list. The problem is that no matter what item I pick, it only displays items based on the default selection.

(The first item in the drop list) Why would that be? Is it because the page reloads and sets the selected value back to the default? (When I stop the page from reloading, clicking on the button produces nothing.)

I've also tried using a sqldatasource but I didn't know how to use the updata parameters.

Umm, thanks a lot in advance.

 

[Markbnj]

I have done that more than once .