?
Solved

VB 2010:  Data from xml... How do I query the data?

Posted on 2010-09-12
13
Medium Priority
?
619 Views
Last Modified: 2012-08-14
My application uses a single (large) xml file as the source for many different reports.  My on_load sub reads the xml into a dataset, and sets a datagridview.datasource to the dataset.

Here's a very simple table in order to explain my question.  Let's say that this is what my datagridview looks like:

Name  Type  Addr
fred      A         123
wilma  B         456
barney C         789

The user then has many different options utilizing the data.  For example:  I need to find all of Type:B, then do something with Name and Addr.

So here are my questions:
1.) Should I query the dataset, or the datagridview, or is there a better approach?
2.) Depending on answer to #1... How?

Can sql query syntax be used somehow?  I know how to run through all the rows in the datagridview, and this is how I've been doing it (but think there must be a better approach):

for r=0 to datagridview1.rowcount-1
  if datagridview.item(1,r).value="B" then
    <do_something>
  end if
next
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        DataSet1.ReadXml("c:\Test.xml")
        DataGridView1.DataSource = DataSet1
End Sub

Open in new window

0
Comment
Question by:motokent
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 6
  • 5
  • 2
13 Comments
 
LVL 18

Expert Comment

by:John (Yiannis) Toutountzoglou
ID: 33656669
try this
For Each row As DataGridViewRow In Me.DataGridView1.Rows
            If Not row.IsNewRow Then
                If row.Cells("Type").FormattedValue = "B" Then
                    do what you want
                End If
            End If
        Next

Open in new window

0
 
LVL 18

Assisted Solution

by:John (Yiannis) Toutountzoglou
John (Yiannis) Toutountzoglou earned 800 total points
ID: 33656688
Or for example
For Each row As DataGridViewRow In Me.DataGridView2.Rows
            If Not row.IsNewRow Then
                If row.Cells("Type").FormattedValue = "B" Then
                    row.Cells("Addr").Style.BackColor = Color.Azure
                End If
            End If
        Next

Open in new window

0
 

Author Comment

by:motokent
ID: 33656709
This is good, but what I'd like to know... is the datagridview approach (your suggestions, and the way I've been doing it) the best appproach?  I've seen things like LINQ to XML where I might be able to avoid datagridview totally, but not sure if there are any benefits to this (such as speed, or simplicity).
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 18

Expert Comment

by:John (Yiannis) Toutountzoglou
ID: 33656720
there is no problem about the performance ...i am using this kind of approach many times,without problem ...
0
 
LVL 64

Expert Comment

by:Fernando Soto
ID: 33656841
Hi motokent;

In answer to your questions:
1.) Should I query the dataset, or the datagridview, or is there a better approach?

    Seeming you are using Visual Studio 2010 I would use Linq to DataSet to do what
    you need.
   
2.) Depending on answer to #1... How?

    See code snippet below.
   
Can sql query syntax be used somehow?  

    Linq has a form that has a syntax of SQL like, see snippet.

Fernando
' This query assumes that the DataTable in question is in the 
' DataSet table zero. Query's the DataTable for all record with
' Field name Type equal to B
Dim queryTypes = From t In ds.Tables(0).AsEnumerable()
                 Where t.Field(Of String)("Type") = "B"
                 Select New With {
                     .Name = t.Field(Of String)("Name"),
                     .Type = t.Field(Of String)("Type"),
                     .Addr = t.Field(Of Int32)("Addr")
                 }

For Each t In queryTypes
    ' Process all Type B records here.
    Console.WriteLine("Name {0}  :  Type {1}  :  Addr {2}", t.Name, t.Type, t.Addr.ToString())
Next

Open in new window

0
 
LVL 64

Accepted Solution

by:
Fernando Soto earned 1200 total points
ID: 33656849
Hi motokent;

If you do not need the DataGridView, DataSet and DataTable you can directly query the XML with Linq to XML.

Fernando
0
 
LVL 18

Expert Comment

by:John (Yiannis) Toutountzoglou
ID: 33656985
Respect !!:)
0
 
LVL 64

Expert Comment

by:Fernando Soto
ID: 33657017
@jtoutou, don't understand your last post?
0
 
LVL 18

Expert Comment

by:John (Yiannis) Toutountzoglou
ID: 33657064
@Fernando  i just like and agree with  your comments...
0
 
LVL 64

Expert Comment

by:Fernando Soto
ID: 33657073
@jtoutou, OK now I understand and thank you.  ;=)
0
 

Author Closing Comment

by:motokent
ID: 33657587
Thanks to both of you.
0
 
LVL 64

Expert Comment

by:Fernando Soto
ID: 33657605
Not a problem, glad I was able to help.  ;=)
0
 
LVL 18

Expert Comment

by:John (Yiannis) Toutountzoglou
ID: 33657610
very very welcome!!
0

Featured Post

[Webinar] Lessons on Recovering from Petya

Skyport is working hard to help customers recover from recent attacks, like the Petya worm. This work has brought to light some important lessons. New malware attacks like this can take down your entire environment. Learn from others mistakes on how to prevent Petya like worms.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This tutorial demonstrates one way to create an application that runs without any Forms but still has a GUI presence via an Icon in the System Tray. The magic lies in Inheriting from the ApplicationContext Class and passing that to Application.Ru…
The ECB site provides FX rates for major currencies since its inception in 1999 in the form of an XML feed. The files have the following format (reducted for brevity) (CODE) There are three files available HERE (http://www.ecb.europa.eu/stats/exch…
This course is ideal for IT System Administrators working with VMware vSphere and its associated products in their company infrastructure. This course teaches you how to install and maintain this virtualization technology to store data, prevent vuln…
This tutorial will teach you the special effect of super speed similar to the fictional character Wally West aka "The Flash" After Shake : http://www.videocopilot.net/presets/after_shake/ All lightning effects with instructions : http://www.mediaf…
Suggested Courses

719 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question