Creating a CascadingDropDown Using AJAX
page 1 of 5
Published: 06 Mar 2007
This article explains the step by step procedure on how to create ASP.NET AJAX CascadingDropDown using data from SQL 2005 Express Database.
by Electronic Screw
Average Rating: 
Views (Total / Last 10 Days): 156976/ 167


I have seen in many forums people asking questions as “how to populate the cascadingdropdown with values from database.” Although there was a sample provided for the same in the ASP.NET AJAX ControlToolkit, most of the learners (novice) following the walkthrough given at get struck at the CarsTableAdapters used in the webservice.

This article explains the step-by-step procedure on how to create CascadingDropDown using database values with the help of Microsoft SQL Server 2005 Express Edition. We will display the models available for a selected car using the cascadingdropdown.

View Entire Article

User Comments

Title: OU812   
Name: BONO
Date: 2012-10-02 10:30:43 AM
you picture links are broken
Title: dfgsdfg   
Name: anitha
Date: 2012-05-30 3:25:23 AM
fsafsdfj sljdkflsdfj sdjflsjdf
Title: testing   
Name: testing
Date: 2012-05-20 2:42:45 AM
Title: ObjectDataSource 'ods_Cars' could not be found.   
Name: Val
Date: 2011-04-02 12:12:32 PM
Great Tutorial thanks a lot! but I have an exception about ods_Cars. Can you explain please where you take it? Thanks
Title: Solution on Error 500   
Name: Vikas Shivaji Dumbre
Date: 2011-03-31 7:51:50 AM
Include below heading in ur Web Service.


it works......
Title: databind selected value - user control   
Name: Jenny
Date: 2010-11-18 3:30:22 PM
Nick -- Could you share the code for the web user control and where you call it? I've been working on the "selected value" (which doesn't want to be selected) all morning!
Title: How to databind selected value   
Name: Nick
Date: 2010-09-23 7:40:09 PM
Hi All,
A few have had problems with databinding a child dropdownlist with the cascadingdropdownextender, I have a solution to this.
I created a user control (.ascx - if you don't know about them you're missing out) and created a read/write property called SelectedValue. Now the 'Get' returns CascadingDropDownChild.SelectedValue, and 'Set' first causes CascadingDropDownParent.SelectedValue = ChildValueForeignKey, and then CascadingDropDownChild.SelectedValue = value. this allowed me to use "SelectedValue='<%# Bind("ChildValue") %>" in the .aspx page.
It seems a bit counter-intuitive, but you get/set the ddl values in the CascadingDropDown extender, not the ddl iteslf.
Hope this helps.
Title: Missing ODS CARS   
Name: Tinda
Date: 2010-02-15 9:17:06 AM
Where this ods cars come from ???
Title: Method 500 or 400 error   
Name: neha
Date: 2010-01-30 4:10:34 AM
Hello,your article is superb and very helpful.thank u vry much. I followed the instruction as u have given,i was able to populate the data in the first dropdownlist but in the second dropdownlist,i m gettin method 500 or 400 error,pls could you help how to overcome frm this situation.
Pls do the needful
thank u in advance,waitin for your reply.. i have to do it immediately.
Title: knownCategoryValues is empty   
Name: Jyotsna
Date: 2009-12-02 11:23:35 AM
Hi, I have 3 dropdownlists and 3 cascading dropdown extenders. I have a webservice method to get the dropdown contents. When I run my aspx, all 3 dropdowns are in a disabled state and I tried to debug and am seeing that knownCategoryValues is empty. How does this field get populated. I'm not using Context Key for the dropdowns. Should I use it. If so, could you explain how? Thanks for your help!
Title: Pick a value from Drop down   
Name: mills
Date: 2009-09-22 10:50:09 AM
Hi, good stuff, but I was wondering how one can pick the displayed value of for example the second drop down list. I have something like

var modelVar = document.getElementById("ddlCarModels").value;
on the onchange event of the MOdel dropdownlist but all I'm getting back is the numerical position 1,2,3,4,5... of the item being displayed but not the actual value being displayed. Can anyone help.
Title: Row Limit   
Name: Rick
Date: 2009-04-03 12:13:20 PM
This article rocks. I have it working properly for 3 dropdowns. Country, Province, City. The province of Alberta has less than 500 cities so that works. Ontario has 1500+ cities so I get the 500 error. Is there really alimit to the number of rows that can be retrieved into a CascadingDropDown? Is there any way around it? (yes it is not good practice to put so many rows into a ddl, however this is one exception where it does make sense)
Title: Amazing Tutorial   
Name: Raj
Date: 2009-03-13 4:24:10 AM

I really liked this tutorial. Keep it up. We did not use adapters but used models called from service to populate the dropdowns.


Title: My error 500 solution   
Name: thunder_mico
Date: 2009-02-10 9:52:47 AM
Awesome tutorial however I kept getting the same error 500 that everyone complaints about.

After uncommenting this line of code
it worked like a charm.

Too bad I didn't read well enough, since the comment above clearly states
// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.

Anyway... I'm posting this for the next person. I'm having a laugh over here.

Great article. Cheers.
Title: Creating a CascadingDropDown Using AJAX   
Name: Thiru
Date: 2009-01-09 7:14:44 AM
hai... i am getting Method Error 500 in DropDownList,
how to resolve,
please give suggission,

Thank u...
Title: nice   
Name: hit
Date: 2008-12-11 9:03:30 AM
good artical but explain some briefly i use this code but not work
Title: No help whatever   
Name: AS
Date: 2008-11-21 2:03:34 PM
This article was no help whatsover. It's full of jargon nobody can understand. I actually found the previous one a lot better, even though that one also had faults.
Title: THANK YOU so so much!!!!   
Name: Kalel
Date: 2008-10-27 11:55:23 AM
Thank you sooo much for this article, you have no idea how much did you help me!

EXCELENT article, very detailed, very very very helpfull!!!

Thanks again!!!!
Title: The type specified in the TypeName property of ObjectDataSource   
Name: dave
Date: 2008-09-18 11:41:04 AM
Thank you VERY MUCH ES for putting this together. this is much more understandable than 'the other' example that assumes quite a bit.

i THINK that I've understood the code presented here and I'm trying to implement my own version using Departments as the first drop down, and employee's as the second.

I'm stuck on the error 'The type specified in the TypeName property of ObjectDataSource 'ods_Cars' could not be found.'

i can't find through the given files as well as this example where ods_Cars is defined. it's only listed twice on the default.aspx page no where else.

any help is greatly appreciated.
Title: Method Error 500 troubleshooting   
Name: Himavath
Date: 2008-06-27 5:06:47 AM
If there large amount of data I am getting Method Error 500, Please help me how to resolve this Issue
Title: use a external class function   
Name: Alex
Date: 2008-06-18 5:04:22 AM
With LINQ.
But it's not returning a DataTable but an IEnumerable(Of T), of course.
Title: use a external class function   
Name: Hideyoshi
Date: 2008-06-18 3:53:08 AM
Is that possible to apply external class function which will return datatable, to a cascadig drop down by using vb? How?
Title: HowTo DataBind in a FormView   
Name: Alex
Date: 2008-06-13 2:17:46 AM
Sorry: SelectedValue='<%# Bind("ModelId") %>', of course.
Title: HowTo DataBind in a FormView   
Name: Alex
Date: 2008-06-13 2:15:24 AM
Suppose I have a DataBound Row in a FormView, e.g. in the FormView I have a person and one of the properties of the person is his dream car. Therefore I would like to use the CascadingDropDown. But I don't know how to DataBind the SelectedValue. I tried something like SelectedValue='<%# Eval("ModelId") %>' at CascadingDropDown1 but it didn't work.
Does anybody have a solution?
Title: Large amount of data - Error 500   
Name: Bianco
Date: 2008-04-22 8:33:43 AM
Someone have the solution for the Service error 500 wich appear while filling the drop down with a large amount of data?
Title: Creating a CascadingDropDown Using AJAX   
Name: yagya nath gautam
Date: 2008-04-16 5:06:09 AM

information is very good.
Title: Method Error 500 AJAX CASACADING...   
Name: regina rodriguez
Date: 2008-03-17 11:24:17 AM
[WebService(Namespace = "")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

the last line is very important !!!!
Title: This topic is really nice   
Name: T H kishore
Date: 2008-03-14 5:23:15 AM
I got the output by using this topic.
Thank u
Title: Method Error 500 troubleshooting   
Name: Arun Vinoth
Date: 2008-02-28 7:13:09 AM
dear all,

Status code 500 indicates an error that occurred on the server( may be before it arrives at the code written by you ), I'd recommend using Fiddler to find out the cause of the problem. The actual error message is returned aside with the response with status code 500, you can use Fiddler to find it out. And the actual error message should give you a clear idea how to solve it.

Title: Excellent Article   
Name: Louis
Date: 2008-01-21 5:55:41 PM
Thank you so much for putting this together. This really helped me out a ton. You rock!

Title: Adding one more dropdown will work fine   
Name: Mohammad Musa
Date: 2008-01-03 3:01:27 PM
In the web service method for the 3rd dropdown you need to get the value of the second drop down correctly.

For my case I used:
string strStateId = _categoryValues[3];

Note index is no longer 1, rather it is 3 now.

This is evident if you run this in debug mode and see what values you get for knownCategoryValues. The format is

First DDL (method #2 to get models):
knownCategoryValues = unknown:{selected value of ddl1};
eg: knownCategoryValues =unknown:1;

for 2nd ddl (method #3 to get colors):
knownCategoryValues ="undefined:1;Model:{value};"
eg: knownCategoryValues="undefined:1;Model:Acura;"

See in above string index of Acura is 3. That is why I used index 3 to get the model name so that I can get the right colors.

If you add one one dropdown then the next index will be 5 and so on.

These basic things must have been cleared in the article.
Hope this helps.
Title: Method Error 500 troubleshooting   
Name: Mohammad Musa
Date: 2008-01-03 2:03:47 PM
Those of you are stuck with this stupid error:
I was having this issue for 5 hours. This seems to be hard to fix if you only have a browser and VS. You need some sniffing tool to see what is the root cause. One such tool is Fiddler.

Just download, install and run it. Any localhost traffic will be caught in fiddler. If you look at the 500 error details, it says No Web Service found ... This line tells that 500 error is coming just because your page is NOT refering to the webservice correctly. Either name is misspelled or method name is wrong or path is wrong.

Also don't forget to test the webservice methods by invoking from asmx page url. That will prove if the method is correct.

Now for my case I was using ajaxToolkit:CascadingDropDown ID="CascadingDropDown1" runat="server" Category="Cars" LoadingText="Please wait..." ParentControlID="ddlCars"
PromptText="Select a model" TargetControlID="ddlCarModels" ServicePath="CarsWebService.asmx" ServiceMethod="GetModelsByCarId"
==> I got 500 error

Then I changed it to the following and it started rocking
ajaxToolkit:CascadingDropDown ID="CascadingDropDown1" runat="server" Category="Cars" LoadingText="Please wait..." ParentControlID="ddlCars"
PromptText="Select a model" TargetControlID="ddlCarModels" ServicePath="../../ajax/CarsWebService.asmx" ServiceMethod="GetModelsByCarId"

==> no error. Note that my service path is pointing correctly where I have put my webservice. Better is to type ServicePath=" and then use VS to browse to the folder where you created your webservice. Hope this helps.
Title: Minor mods req to work with Access 2003   
Name: jeeef
Date: 2007-12-31 5:34:21 PM
Very good example, had some trouble when the CarModelsTableAdapter was not correctly created, worked on third attempt(first 2 tries I went too fast for VS to create the table adapter object). When used Access 2003 instead of SQL Server 2005 had to change the call to:
SELECT ModelId, CarId, ModelName
FROM CarModels
WHERE (CarId = ?) and cast the _carID to short for WebService call to work... GetModelsByCarId((short)_carID)

Thanks for the example to play with!
Title: loading values to cascading dropdown list   
Name: jon diaz
Date: 2007-12-17 11:50:04 AM
Hi everybody,

Nobody knows how to set SelectedValue in code behind?

Title: fanatastic article   
Name: ado
Date: 2007-11-20 8:25:09 AM
the article is excellent but i try to use three dropdowns i failed ,can anyone help me
Title: Good Code   
Name: mike
Date: 2007-11-06 9:25:57 AM
this should be in the sample page...
Title: awesome   
Name: sam
Date: 2007-10-27 12:49:51 AM
awesome, man...
microsoft example sucks...
Title: 500, 12031method error   
Name: jyothi.p
Date: 2007-10-26 3:07:02 AM
I proceeded in the same way, as detailed in article. but no use. Getting method error 500/12031..
Any pointers
Title: wheres the data?   
Name: Mark
Date: 2007-10-02 6:16:04 AM
Hi, I was just wondering where the data comes from as we create the tables from scratch. Do we import them from somewhere or input them manually? When you run the sample download it has the drop downs populated. Am I missing a step? This article is very helpful. I agree with the original posting, the previous run through solution wasn't designed for beginners.
Title: 500/404 error   
Name: Saravanan
Date: 2007-09-17 5:48:27 AM
This article Is nice ,it is very useful for me,
but i have an problem,i do the thing as u told above, but it showing 500/404 error please reply


Title: ajax drop down   
Name: mithlesh
Date: 2007-09-16 10:59:13 AM

I am mithlesh.I want use drop down in asp and when i have problem.i have three drop down like state,city and location.
when i choose state it show city according to state and when choose city it show location according to city and state without refresh form.i dont want refresh form.plz help me.
Title: How do you bind the cascading dropdown to set selectedvalue   
Name: Jan Steenberg
Date: 2007-08-21 3:14:03 AM
It looks good. I Have the challenge that i want both dropdowns to have a selectedvalue set automatically from the database fields on my detailsview.
Title: This is a great article but Can it be donw using Oracle as a backend?   
Name: Developer in distress
Date: 2007-08-17 4:13:36 PM
This article is very informative but I use Oracle as my database of choice. Can I still use the CascadingDropDown with Oracle? I can't seem to fine any articles that address this form of datastorage using the Cascading DropDown.
Title: Great article, but do you VB version?   
Name: Muzi
Date: 2007-08-08 7:33:10 PM

I'm VB person so C# doesn't work for me, please will you post a VB version.


Otherwise this is what I've been looking for!
Title: The type or namespace name 'dsCarModelsTableAdapter ' could not be found (are you missing a using directive or an assembly reference?)   
Name: vamsi
Date: 2007-08-04 3:32:00 AM
i am getting the following error while building

The type or namespace name 'dsCarModelsTableAdapter ' could not be found (are you missing a using directive or an assembly reference?)

and i am not able to get the "dsCarModelsTableAdapter" in my page

any suggestions???
thanks in advance..
Title: nitin   
Name: nitin khadloya
Date: 2007-07-18 8:10:26 AM
very nice articles
Title: RE: Runtime Error: NullReferenceException   
Name: name
Date: 2007-07-16 12:03:35 PM
I had the same problem because my dropdown list was in a Formview control and the extrender was outsite. It was easily fixed by putting the extender inside the formview
Title: Method Error 500, 12031   
Name: roopa
Date: 2007-07-13 5:52:08 AM

I proceeded in the same way, as detailed in article. but no use. Getting method error 500/12031..
Any pointers

Title: One More Parameter   
Name: Electronic Screw
Date: 2007-06-17 9:29:11 AM
That is not possible with the current method syntax of the CascadingDropDownList. The method takes only 2 parameters. One alternative is to pass both the values as a single parameter separated by a char value to the knowCategoryValues and before you call your select command you split the value to get the carId and userId.

Title: One More Parameter   
Name: Siva
Date: 2007-06-15 11:19:57 AM
My second query goes like this...

SELECT ModelId, CarId, ModelName FROM CarModels WHERE (CarId = @carId and UserID=@UserID)

Any idea how do I pass @userID to the second method GetModelsByCarID??

GetModelsByCarId(string knownCategoryValues,
string category)

Title: Runtime Error   
Name: Brian
Date: 2007-05-24 2:14:35 AM
John, I'm getting the same error. Did you ever find out what caused your error?
Title: Runtime Error   
Name: John
Date: 2007-05-17 7:07:50 AM

I an getting this error at runtime:
"Object reference not set to an instance of an object."
And the Stack Trace:
"[NullReferenceException: Object reference not set to an instance of an object.]
AjaxControlToolkit.CascadingDropDown.CascadingDropDown_ClientStateValuesLoaded(Object sender, EventArgs e) +98
AjaxControlToolkit.ExtenderControlBase.LoadClientStateValues() +240
AjaxControlToolkit.ExtenderControlBase.Page_PreLoad(Object sender, EventArgs e) +5
System.EventHandler.Invoke(Object sender, EventArgs e) +0
System.Web.UI.Page.OnPreLoad(EventArgs e) +86
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +948"

Now this might be trivial to some of you, all I did was follow the tutorial step by step and corrected some syntax errors I had at compilation. I did not change (or add) anything to the code presented in the tutorial as I wanted to see it working before I could change some stuff.

All help aprreciated,
Title: Maximum number of tiems in the dropdownlist   
Name: Hosam Salem
Date: 2007-05-16 2:51:45 AM
Dear All,

Does a DropDownList controlled by the CascadingDropDown Control has a maximum number of items to be displayed in it?

This is the case i have, it works for items <= 774, but, after this limit, it gives the famous eeor [Method Error 500] :(

Another post here is talking about the same issue:

Any ideas?
Title: Daniel Avenel   
Name: Electronic Screw
Date: 2007-05-10 5:42:42 AM
Hi Daniel,

Sorry for the late reply. I am not sure how i missed your post. Could you please write in details whatz happening when you get the exception by keeping a break-point and debugging?

Title: 3rd dropdown list   
Name: Pete
Date: 2007-05-09 11:50:12 PM
North, Thank you for your help with the 3rd cascading ddl. Now I got it to work. You rock!
Title: loading values to cascading dropdown list   
Name: sujith
Date: 2007-05-07 7:19:34 PM
Hi thr,
the article is very explanatory. everything is working well but the issue i have is with the loading of the dropdown list at page load. for instance, if i need to get the value from the database at the page load and initialize teh dropdown list with that value, its not working.for ex, if i use the statement Dropdownlistmodel.selectedtext="AUDI" in the page load ,the selected value still remains "Please select a make". i have tried debugging and what i observe there is that the webservice is being called after the page load event which is causing it to load the dropdown list from the webservice after the page load. it would be great if you could help me out with any possible solutions for this.
Title: Source Files Available?   
Name: Electronic Screw
Date: 2007-05-05 9:23:36 AM
If i am not wrong, the source code for the article is still available for download in the download section. Alternatively you can download it from the location:

Title: Source Files Available?   
Name: KBrown
Date: 2007-05-03 5:40:00 PM
Very Nice Article!
Are the source files available for download? I don't see them under download. TIA.
Title: 3 dropdown lists   
Name: north
Date: 2007-05-02 3:33:03 PM
reply to: PETE - Re: 3 drop down lists

I needed a solution like such that uses 3 drop down lists, each built from a selection in a prior list.

For example. Country, State, and County dropdownlists

Firstly, I switched all this code to VB because well that's what I most comfortable with. I used this guide to get the 2 dropdown list example here functional for me, then tackled the third.

The trick is in the 3rd dropdown getDataByID(@ID,ID2) method in the WebService.

Pay attention to these lines of code with explanation

string[] _categoryValues = knownCategoryValues.Split(':', ';');
// KnownCategoryValues looks something like USA:Country;NY:State;
//so when you split it out (by ; and :), the variable string[] array becomes
// [1] USA
// [2] Country
// [3] NY
// [4] State

and so on. But the first pair before the first ; is the value, and category (@ID param name) of the first drop down
and the second pair id my second drop down selection (VALUE: @ID2 param name)

then add a second varibale to collect the secong pair data

ID1 = _categoryValues[1]; <-- will get the 1st ddl Value
ID2 = _categoryValues[3]; <-- Will get the 2nd ddl Value

so for multiple variable Dataset in a getDataByID(@ID1, @ID2) method you now have both variables, I assume this could go on forever with Parent Cascading Links.

I used VB so my conversion back to C# above might not be great, but hopefully the idea is presented clearly
Title: 3 dropdown lists   
Name: Pete
Date: 2007-04-27 2:27:43 PM
I tried using the same code to add a 3rd dropdown list with no luck on the 3rd. I added a 3rd database using the same basic code wording. It works perfectly with 2, as per following your tutorial. Thanks in advance.
Title: Method Error 500 - retrun array contains data   
Name: Daniel Avenel
Date: 2007-04-23 12:39:54 PM

I have followed the principals you lay out here & continue to get an Method error 500. In stepping through the code, I can see that the CascadingDropDownNameValue collection is building & in fact has all the data. The error seems to ocur upon returning the Collection. Any help would be great. One note, I have built this in an "AjaxEnabledWebApplication", and as such the codebehind of the asmx is NOT in App_Code as in your (and other) examples, but the code never the less is executed.

Title: No overload for method 'GetLeerlingByOV_nr' takes '1' arguments   
Name: Electronic Screw
Date: 2007-04-21 1:40:25 AM

Check your _LL_NaamAdapter.GetLeerlingByOV_nr signature. The error says there is no overloaded methods which takes a single parameter as you are passing it. Keeping the cursor on the method name will show you the method signature.

E Screw
Title: 'CCDFromDatabase.Properties.Settings' is inaccessible due to its protection level   
Name: Electronic Screw
Date: 2007-04-21 1:38:01 AM
Could you let me know how you are storing the connectionString?

E Screw
Title: No overload for method 'GetLeerlingByOV_nr' takes '1' arguments   
Name: I am seeing things?
Date: 2007-04-20 6:58:36 PM
i am totally lost now, while the error says to me, that the method i am calling without/more than the assigned argument(s). i cant imagen _ov_nr isnt an argument, even if its empty. any hints / comments / solutions are very welcome!

i am getting the error:
"No overload for method 'GetLeerlingByOV_nr' takes '1' arguments"

On the sentence:
foreach (DataRow _row in _LL_NaamAdapter.GetLeerlingByOV_nr(_OV_nr))

The query i try to execute is:
SELECT OV_NR, LL_Naam, LL_Achternaam from leerling where (Ov_nr = @_Ov_nr)

ps. the guide-version works perfectly, just the adjusting on my own situation isnt working.
Title: 'CCDFromDatabase.Properties.Settings' is inaccessible due to its protection level   
Name: Need Help!
Date: 2007-04-19 10:39:33 AM
Help! Does anyone know how to fix this error: 'CCDFromDatabase.Properties.Settings' is inaccessible due to its protection level

private void InitConnection() {
this._connection = new System.Data.SqlClient.SqlConnection();
this._connection.ConnectionString = global::CCDFromDatabase.Properties.Settings.Default.JEMSConnectionString;}
Title: greate   
Name: kamlesh
Date: 2007-04-19 5:46:54 AM
this is a very nice article on cascading dropdown , u make me and many more to understand what is happenning in webservice thanks alot
Title: dsCarModelsTableAdapter cannot be found   
Name: Linda
Date: 2007-04-18 3:46:57 PM
Figured out my problem... I had to change it to: CCDFromDatabase.App_Code.dsCarModelsTableAdapters.CarModelsTableAdapter _carModelAdapter = new CCDFromDatabase.App_Code.dsCarModelsTableAdapters.CarModelsTableAdapter();
Title: dsCarModelsTableAdapter cannot be found   
Name: Linda
Date: 2007-04-18 2:40:26 PM
The type or namespace name 'dsCarModelsTableAdapters' could not be found (are you missing a using directive or an assembly reference?)
Title: Can't run it   
Name: Electronic Screw
Date: 2007-04-12 3:36:19 AM
Ina, Could you please write me in detail about the problem? Do you have any error/exception raised? I would also suggest you to download the source code provided and check if its working with your or not!

Title: this is cool   
Name: Mousakaaaa
Date: 2007-04-11 8:39:40 PM
this is cool, just what I was looking for and a good teaching aid, I needed to tweak it a little to run for me, but that is the only way we will learn ! thanks for taking the time and effort to put this together for us
Title: Can't run it   
Name: Ina
Date: 2007-04-04 6:04:26 AM
Web service methods return prover values, but nothing is loaded into dropdown lists I use :-(
Title: ERROR 500   
Name: Electronic Screw
Date: 2007-04-04 2:27:06 AM
Check this thread: This thread explains the different causes for the Internal Server Error 500. You can also download the code and test it. I guess you might have missed a static keyword for web method, incorrect parameter names etc., Do let me know if the problem still persists!
Title: ERROR 500   
Date: 2007-04-03 6:32:13 PM
Title: still can't get any of these CascadingDropDown examples to work!   
Name: Electronic Screw
Date: 2007-03-29 2:23:44 AM
It depends on how you want to fetch the data, either you use datasets, or go for a generic list, the article explains on how to retrieve the values from database to a cascading dropdown list. I dunno why you are unable to make a data connection. You may need to check your connection strings, access permissions etc. You can also download the complete working source given with the article, assuming you have ASP.NET AJAX 1.0 library installed.
Title: still can't get any of these CascadingDropDown examples to work!   
Name: mark4asp
Date: 2007-03-28 11:22:01 AM
It didn't quite work for me, my PC won't make that data connection (due to a security problem?). I shall drop the silly datasets used in this example (not very real world is it?) and use a data reader into a generic list - then I'll try again. First I'll try to run the authors code to see how it differs from mine.

I still can't get any of these CascadingDropDown examples to work!

Does the CascadingDropDown really not need a ScriptManager?
Title: Thanks   
Name: Electronic Screw
Date: 2007-03-27 5:19:33 PM
Thanks Jesse and Mark!
Title: Cascading with Sql Reader   
Name: Jesse
Date: 2007-03-27 1:36:13 PM
Great stuff! I wrote something up a little while ago using the SQL Reader to use SQL Express as well!648485A03D9E8213!1380.entry#comment
Title: Nice   
Name: Mark Wisecarver
Date: 2007-03-27 7:57:21 AM
Very well done.
Title: Re:   
Name: Electronic Screw
Date: 2007-03-09 3:26:17 PM
Thank you Scorpion
Title: Scorpion_hpvn   
Name: Doan Thanh Nhan
Date: 2007-03-09 5:25:32 AM
Thank, it is very good tutorial

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