Dynamically Populate Dropdown from Dropdown?

[p8katcaj]

I have an ASP.NET web form that is used to enter technical notes about our software products. There are two dropdowns on this page, one that lists each software product we have, and another that selects which version of the product is needed.<BR><BR>I would like to know if there is a way to have the version dropdown dynamically load the appropriate software versions depending on which product is selected in the first dropdown, and if it can be done WITHOUT hitting the submit button?<BR><BR>By the way, just to be clear, both of these dropdowns are populated from a database. I don't have a problem doing a select * from the Version table so that all the appropriate versions are in a disconnected recordset, I just can't seem to figure out how to change those items dynamically without resubmitting the page.<BR><BR>-Todd Davis<BR>[email protected] this<BR><BR><asp:dropdownlist ID="dropdownlist" OnSelectedIndexChanged="showprogram_click" AutoPostBack="true"><BR><BR>Sub showprogram_click(ByVal sender As Object, ByVal e As EventArgs)<BR>put your select statement here<BR>End IfThe above method will work but it does a page reload. They only way I think it could be done is with a webservice. I haven't worked with them much though but you might want to look into them. I do konw they require IE 5.5 or something high like that so its not any good for public use applications.If your total list of items is small (less than 200, i'd say), you should try to do something like what they have on the home page for CarsDirect.com.<BR><BR>They have their entire list of Makes as a static drop down list, then when you select one, it populates the 2nd ddl (Models) using javascript. I had to do something similar for a client of mine for States and Major Markets and Cities (YIKES!) and I used the same technique.<BR><BR>I SUGGEST THAT YOU RESUBMIT THE FORM! There are a lot of issues with using javascript to clear and re-populate the 2nd ddl. You will run into the following:<BR>* In Netscape, when you start out with an empty, the ddl will only display ONE item in the ddl at a time when you click the down arrow - even if you add 100 items. If you want to scroll down to the last item in the list, you will have to click the down button many times. I think you can get around this by padding the list with blank items, but the results are sporatic.<BR>* There is a problem with Netscape not resizing the ddl's width to accomodate the longest item when you repopulate. To get around this, you need to specify style="width:175px;" or whatever the longest possible item may be.<BR>* If the list is database driven, then generating this list every time is costly because it usually requires recursive db calls. I got around this by saving the entire javascript as an application variable, but whenever you make changes, you need to re-generate the js code.<BR>* It's just a pain in the ***. I would avoid this unless ABSOLUTELY neccessary.