Search VB 2010

Showing posts with label VB 2010 Optimization. Show all posts
Showing posts with label VB 2010 Optimization. Show all posts

Wednesday, February 05, 2014

Visual Basic Online Course - Read Text File

Visual Basic 2010 - How to Read Text File(s)

VB 2010 Read Text Files
VB 2010 Read Text Files
Introduction

In order to read from a Text File then a Text File has to be present (Present = Known Path), the path of a Text File is just like any other path of any file it is String, for example :
C:\Folder\File.txt
The path to the File.txt is (C:\Folder\File-Name.Extension), so the path to the File Text = Path + File-Name + extension. Text Files can be present locally (on the same machine) or from external place (on the web) for example :
ftp://10.0.0.27/Folder/File.txt
As long as this Path is present and accessible then Reading Text File in VB 2010 is just so easy job to do. We can store the path to the Text File into a String variable to use it in our VB 2010 project :
Dim LocalFilePath as String = ("C:\Folder\File.txt")
Dim WebFilePath As String = ("ftp://10.0.0.27/Folder/File.txt")
The problem with Text Files hosted on the web, is that it has to be accessible in order to read it or write it, you have to provide  a User Name and Password to gain access to those files for most of the times because of security issues, unlike reading Text Files from local storage devices, there is no need to provide credentials or authentications to be able to read them.

Reading from Local Text Files in VB 2010

We will use File Reader to read String stored in a Text File,we will use basics of reading Text Files.

1) Create VB 2010 Windows Form Project (WindowsApplication1) and save it to (D:\)
2) Add TextBox (Name : TxtFromFile, MultiLine : True)
3) Create Text File (MyFile.txt) and place it in the project folder
Path to MyFile.txt is (D:\WindowsApplication1\Bin\Debug\)
4) Write to MyFile.txt those two lines :
Hello
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5) Save and close the file.

Now, the project will :
Open the Text File to read on the Form_Load() event
Displays the String in the TextBox (TxtFromFile)

Code


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Sunday, December 15, 2013

Visual Basic Compare Two Treeviews and return differences

Visual Basic 2010 - Compare Two Strings and return differences and matches

vb2010 compare strings and return differences
VB2010 Compare Strings in Collections

Collections as an Alternative to Arrays

Visual Studio 2010
Although collections are most often used for working with the Object Data Type, you can use a collection to work with any data type. In some circumstances, it can be more efficient to store items in a collection than in an array.



If you need to change the size of an array, you must use the ReDim Statement (Visual Basic). When you do this, Visual Basic creates a new array and releases the previous array for disposal. This takes execution time. Therefore, if the number of items you are working with changes frequently, or you cannot predict the maximum number of items you need, you might obtain better performance using a collection.

A collection, which does not have to create a new object or copy existing elements, can handle resizing in less execution time than an array, which has to use ReDim. But if the size does not change, or changes only rarely, an array is likely to be more efficient. As always, performance is highly dependent on the individual application. It is often worth your time to try both an array and a collection.

This Example

How to compare two Treeviews in VB2010
How to return the differences between two Treeviews

Solution

- Create Visual Basic 2010 Windows Application Project
- On Form1, place two tree views and two textboxes and one button

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Visual Basic 2010 Compare Strings from Treeview
How does it work ?
- Store the Treeview1 [TRV1] nodes into Textbox, and the same with Treeview2 [TRV2]
- How many strings [Lines] in each Textbox

  • We want to find where both Textboxes is different and where both Textboxes is match to one another. For example, differences are :
- TRV1 has an extra string [Southern American]
- TRV2 node string [Africa] is different from TRV2 node string [African]

Steps to accomplish this task :





Download example from Mediafire
Extended work :
You can easily extract any Database tables, columns Schema into a treeview control, and you can also using this example compare two tables or two columns in a Database using this example as well.

You can use ListViews or ComboBoxes or ListBoxes instead of the Treeview control, I used the treeview control because it's always tricky to work with. Using other controls that store strings in Collection format would be so easy, even much easier than using Treeviews.

Another Treeview Examples

Expand and Collapse two treeviews at the same time according to one another even if they both don't have the same nodes names. Expand TreeView1[TRV1] node when TreeView2 [TRV2] node is expanded or collapsed.

TreeView Example : Change the node font

TreeView Example : Add a photo (icon) to the TreeView
1) Add ImageList from the ToolBox
2) Add 2 photos to the ImageList1 [From properties, Collection], for example :
- Photo1.Png (Index by default is Zero 0), this will be the Parent icon
- Photo2.Png (Index by default is One 1), this will be the first child icon
3) Code to display image/Icon in the Tree View :


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Friday, December 09, 2011

Solution - There is already an open DataReader associated with this Command which must be closed first.

VB 2010

Problem : There is already an open DataReader associated with this Command which must be closed first.
Cause : Having more than 1 dataReader result set working at the same time .
Solution : In my solution example, i work with SqlServer2000 and VB.Net 2005 
The Example Project can be downloaded at the end of this post :
It contains (SqlServer2000 DataBase - VB.Net Project)
The example shows how to navigate (First Record - Next Record) using ADO.Net 2.0 Online-Mode using SqlClient DataReader ...
Sql Database Name : Market
Sql Database Table : Market.Info
Server Name : evry1falls
(in order to see the example correctly, you'll have to Import the Database 'Market' into your sqlserver2000 Enterprise Manager)
Photo1 : Application Final Design
Photo 1












Photo2 : Table Structure
Photo 2







Photo3 : Codes
Photo 3






Photo4 : Codes
Photo 4







Photo5 : Codes
Photo 5








Now if you run the project and tried to navigate using (First) or (Next) you will get the Exception :
There is already an open DataReader .....
so the solution would be :
Trap the Exception that shows in the (SelectedIndexChanged) Event of the (ComboBox) like this :

and the same for the (Next) Button ..
now you can Navigate and search using combobox safely without exceptions ..

Note :
- Source code will give you exception and you will have to re-write the solution by yourself  as shown above .
- The Folder(Bin/Debug) Includes (Back-Up) use it to restore the (Market Database) in your sqlserver2000
- use the namespace (evry1falls) as new server Registration .

Download Source Code : MediaFire Link

Using MS Access 2003/2007/2010

- In case of using Microsoft Access Database, OleDb.OleDbDataReader with OleDb.OleDbCommand.

The work around or the solution would be :
Always create a new Instance of the OleDbCommand, I.e

Monday, May 16, 2011

VB 2010 Create Controls at Run-Time with events

How to Create Controls at Run-Time in 

VB 2010

VB 2010 Create controls at run-time
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Logic

The example will show you how to create a control (TextBox) at the Application Run-Time. This TextBox will allow only Numbers. We will create a new TextBox control with event  Text Changed when the form is clicked

Project Design

Create new VB 2010 Windows Application Project (MyPro), don't forget to always Save your project

How does it work

You RUN your project and then click on the Form (Form1) and then you will notice that a TextBox control was created with the same properties that we provided in our example in the code below.

TextBox Properties

Location : The cursor location when click on the Form1
Size : 120,300
Parent : Form1 (Me)
TextAlign : HorizontalAlignment.Left
ForeColor : Color.White
Name : MyNewText
Font : Times New Roman, 10, Regular, Point

Code

Thank you for reading ....

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Thursday, November 25, 2010

Visual Basic 2010 with MS-Access Database

Understanding ADO .Net for Visual Basic 2010 and Microsoft Access 2003 / 2007 Database

Visual Basic .Net and Ado.Net for MS-Access Database course online
There are two methods to work with MS-Access 2003/2007 Database (*.Mdb / *.Accdb) from Visual Basic 2010 using ADO .Net technology .
With .NET, Microsoft has released a new mechanism for accessing data: ADO.NET. The name is a carryover from Microsoft's ADO (ActiveX Data Objects) technology, but it no longer stands for ActiveX Data Objects--it's just ADO.NET. To avoid confusion, I will refer to ADO.NET as ADO.NET and to ADO as classic ADO.
If you're familiar with classic ADO, be careful--ADO.NET is not a descendant, it's a new technology. In order to support the Internet evolution, ADO.NET is highly focused on disconnected data and on the ability for anything to be a source of data. While you will find many concepts in ADO.NET to be similar to concepts in classic ADO, it is not the same.

Method (1) Online mode
Online-mode is just like the same old method we used to work with Databases from Visual Basic 6.0 and ADO2.8 version, all you need to do is :
    • Create Access Database and a Table with your fields.
    • Define the Database path
    • Include ADO2.8 Reference into the Visual Basic 6.0 project
    • Connect the Database
    • Open the Database
    • Operate your events (Save, Edit, Delete and find)
    • Exit the VB6 Project and you will find the data in the Table were affected if events were processed correctly in the VB6 Project.
 And the this is the same logic with ADO.Net in Visual Basic 2010 and MS-Access 2003/2007. The difference is in coding interface, but also the logic is the same some how, more than VB6 Coding, but more understandable.

An example to the Online-mode with MS-Access 2003, is the Friends_Info. Basic code to connect to a MS-Access Database  2003/2007 from Visual Basic 2010 using the ADO.Net Online-Mode is :
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♦ Connect to and Open Database :

♦ Save Data into Table :

♦ Search for Data :

♦ Delete Data from Table :



Method (2) Offline mode
ADO.Net Offline Mode

You will see the difference now of using ADO technology only if you are familiar with classic ADO that we used to use in Visual Basic 6.0, but if you did not use it before that you won't.
ADO.Net Offline mode or the Disconnected method of working with Databases has a nice and easy logic :
♦ ADO.Net Offline mode works great with Client/Server applications
ADO.Net method is the preferred way to code client/server applications. The DataSet object is what the ADO.Net offline/Disconnected mode is all about, it gives you the ability to work on the Database components separately (it stores a Database copy in the Memory - RAM of the client machine while working on the Database components), so it gives you the ability to create multiple tables, fill them with data coming from different sources, enforce relationships between pairs of tables, and more.
 ♦ ADO.Net Offline mode is not recommended for ASP.Net
Though the Dataset is a great choice to work with Client/Server applications, but when working for example with ASP.Net live pages, it is a bad choise because the ASP.Net pages don't live long before they finish their lifetime cycle.
The above Friends Info VB.Net project using ADO.Net offline mode basic codes as follow :
Connect to and Open Database :

Save Data into Table :

Search for Data :

Delete Data :

I will discuss working with Crystal Reports for Visual Basic .Net in details in another post, starting Downloading SAP Crystal Reports until Packing SAP Crystal Reports and install it on the client's machine. Keep up !
Another topic about ADO.Net generally, is the ability to Create/Delete/Back-up Database, Add/Modify/Delete/Back-Up  Tables and Queries using the OpenSchema method. Let's see how to do this in Visual Basic .Net 2010.

VB2010 : To Create new Database using ADO.Net, you will need to add new reference to your project to  AdoX (Microsoft ADO Ext. 2.x for Dll and Security) ...
VS2010, ADOX, ADO.Net, MS-Access
Create new Database in Visual Basic 2010
VB2010 : To list all Database files from a Dir. into a TreeView control

VB2010 : To manage Tables using OpenSchema method

 VB2010 : To manage Fields using OpenSchema method

 

Some Visual Basic Exceptions and Solutions Working with MS-Access 2003/2007

Exception: "Dynamic SQL generation for the UpdateCommand is not supported against a SelectCommand that does not return any key Information"
Solution  :

Exception: "Syntax error (missing operator) in query expression ''He's')'.", while trying to Execute INSERT INTO Statement which carries String Values that contain Apostrophe like (He's)"
Solution :


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