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Old December 19th, 2004, 10:42 PM
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Default Dropdownlist Database Connection

I need helps.


Consider in a page i have two dropdown list. First dropdownlist displays DESCRIPTION and depending upon the selection of DESCRIPTION in first dropdownlist, i need to display DESCRIPTION SUMMARY in second dropdownlist. All of the data i get from SQL database.

First Dropdownlist SQL connection ( Success )-->
Const strSQL As String = "sp_GParam 'SELECT', '45', '', '', '', '', '', ''"

Second Dropdownlist ( Failed )-->
Dim SQLstr As String = "sp_GParam 'SELECT', '" & "ddlMainCat" & "', '', '', '', '', '', ''"

In the second dropdownlist, i want to populate the data by refer in first dropdownlist.


i want to use this method-->

After selecting a value from the DESCRIPTION dropdownlist. i can do a postback and get the data for DESCRIPTION SUMMARY and bind it to the other dropdown. This method involves a page refresh. All the controls in the page have to be refreshed and whatever data entered has to be retained.user has to wait till the page loads for entering other data in the page.

Can i discuss about all of it with anybody. I need to be more experiences in asp.net because i'm really beginner for it.

Thanks A Lot..


Syed
 
Old December 19th, 2004, 11:40 PM
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The .NET programming model is built around postbacks. If you want to build a page that doesn't use postbacks, you have to write a lot of client-side script to handle the changing data when the user changes the selected option in the dropdown list. There is no built in capability to do this in .NET.
 
Old December 20th, 2004, 04:39 AM
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Thanks for the reply..

I really dont understand what do you mean by no built in capability to do this in .NET. Actually i use a postback to get my Second dropdownlist population but i think there is something wrong with my code or my coding technics. Take a look of my code-->

Const strSQL As String = "sp_GParam 'SELECT', '45', '', '', '', '', '', ''"

This is for my fisrt dropdownlist. I call from my SQL Server 2000 Stored Procedure and it's success. The value '45' inside the database are refer to-->

GroupID ItemID Description
45 46 Where To Stay
45 47 Where To Eat
45 48 What To Do
45 49 Getting Around
45 50 Popular Destination
45 52 Quick Info
45 53 Map
45 51 MainPage

Everything(DESCRIPTION) inside my first dropdownlist are successfuly populate.

in my second dropdownlist-->
Dim SQLstr As String = "sp_GParam 'SELECT', '" & "ddlMainCat" & "', '', '', '', '', '', ''"

For my second dropdownlist, i refer the value from my first dropdownlist. Let say i choose Getting Around from my fisrt dropdownlist. Its will become-->

GroupID ItemID Description
49 05 LRT
49 01 By Air
49 02 By Railway
49 03 Road
49 04 Monorail
49 06 By Sea

So, if i choose Getting Around description, my Second Dropdownlist should populate all value inside the DESCRIPTION.

Do you mind if you give me your comment, Please. I'm really confuse and lost focus right now.



Syed
 
Old December 21st, 2004, 07:38 AM
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Please anybody, give me advice and help me to find the solution because all my task depends on second dropdownlist.

Syed
 
Old December 21st, 2004, 04:44 PM
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The problem is how you are constructing your SQL statement...

What you originally have:

SQLstr = "sp_GParam 'SELECT', '" & "ddlMainCat" & "', '', '', '', '', '', ''"

will result in this:

sp_GParam 'SELECT', 'ddlMainCat', '', '', '', '', '', ''"

which SQL will not understand because it will look for a value of 'ddlMainCat'.

What you want is this:

SQLstr = "sp_GParam 'SELECT', '" & ddlMainCat.SelectValue & "', '', '', '', '', '', ''"
 
Old December 21st, 2004, 09:54 PM
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Yeah, as what planoie is saying you must not placing (") mark in front of your webcontrol id. the system will assume that you're looking for text ddlMainCat in your DB. So, second ddl shall declare as this:

Dim SQLstr As String = "sp_GParam 'SELECT', '" & ddlMainCat.selectedvalue & "', '', '', '', '', '', ''"

and please make sure your first ddl (that is ddlMainCat) has AutoPostBack that is set as true (in your HTML code).

Besides, I suggest that you call out your second ddl in between this codes in your .aspx.vb file.

Private Sub drpBatchUsing_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles drpBatchUsing.SelectedIndexChanged
.
.
.
Dim SQLstr As String = "sp_GParam 'SELECT', '" & ddlMainCat.selectedvalue & "', '', '', '', '', '', ''"
.
.

End Sub



 
Old December 22nd, 2004, 11:01 PM
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Thanks everybody. I will try it first and hope its success. I will tell you if i'm success or not. Thanks a lot.

Syed





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