Software Code Help blogs

Problem: TableAdapter generated by visual studio designer, not saving data in database

Sandeep Bhutani — Thu, 13 Nov 2008 04:55:41 GMT

Hi.

I have created a Typed Data Set using visual studio 2005 designer. I drag-dropped a table from database and it created a typed data table into it. When I insert data into this table using TableAdapter generated by Visual sudio designer it does not insert in physical database.

I can retrieve it till application is running and lost as the inserted data is in memory not in physical database.

here is the sample code I wrote:

DefectTrackerDataSetTableAdapters. tblDefectsTableAdapter ta = new DefectTracker.DefectTrackerDataSetTableAdapters.tblDefectsTableAdapter();>

ta.InsertDefect( Convert.ToInt32(txtDefectNo.Text), "MQC", dpAssignDate.Value, "Open");>

What is JITCompiler Function?

Raj Shekhar — Thu, 06 Nov 2008 05:25:33 GMT

1. In the assembly that implements the type(Console), look up the method being called in the metadata.
2. From the metadata, get the IL from this method and verify it.
3. Allocate a block of memory.
4. Compile the IL into native CPU instructions: the native code is saved in the memory allocated in step#3.
5. Modify the method's entry in the Type's table so that it now points to the memory block allocated in Step#3.
6. Jump to the native code contained inside the memory block.

How to concatenate the field value of table in SQL Server 2000 or 2005?

Raj Shekhar — Thu, 06 Nov 2008 04:56:38 GMT

Declare @Var1 nvarchar(800)

Set @Var1=’’

Select @Var1 = @Var1 + ‘,’ + Field1 from Table1

Select @Var1

Unable to strat debugging on the web server. The COM+ registry database detected a system error

Sandeep Bhutani — Mon, 13 Oct 2008 10:28:18 GMT

Problem:

I am getting following error while running the project in Visual Studio 2005 by hitting F5

"Unable to strat debugging on the web server. The COM+ registry database detected a system error."

what can be the cause?

Answer

After searching some internet,
I added the ASPNET user to Local Administrator group and restarted IIS and it started working.

However somewhere it is written that even after removing from Administrator group it kept on working, but not in my case. I removed from the group and restarted IIS and it stopped working again.

SFC /Scannow asks for CD always

Sandeep Bhutani — Wed, 17 Sep 2008 11:41:06 GMT

Hi,

Whenever I run sfc /scannow it asks for a CD. How can i point it to some other path where my installation source files reside.

Answer:

In Registry using regedit locate

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\Setup\SourcePath

Set its value to the location where I386 foler is located. Provide the parent folder path of I386 and not of I386 itself.

Also update ServicePackSourcePath and add to Installation Sources as well.

postback with showModelessDialog

Sandeep Bhutani — Mon, 01 Sep 2008 03:57:27 GMT

Question:

HI,

I have got a strange problem. I am opening a webpage using javascript's showModelessDialog fuction. the page contains a calender.

When I click a date on calender (opened with showModelessDialog) it openes a new window showing the javascript function like: javascript:__doPostBack('MyCalendar','3132')

Please provide your valuable comments.

Answer:

use :

in the showModelessDialog or showModalDialog page in head section.

How can I get the selected text from a TextBox?

Sandeep Bhutani — Mon, 01 Sep 2008 03:50:18 GMT

here is the working code:

<div>>

<asp:TextBox runat="server" ID="txt1" TextMode="MultiLine" />>

<asp:HiddenField runat="server" ID="hidSelectedText" />>

<asp:Button runat="server" ID="showselected" Text="Show selected" OnClientClick="doselection();" OnClick="showselected_Click" />>

function doselection()>

{

if (window.getSelection)>

{

txt = window.getSelection();

}

else if (document.getSelection)>

{

txt = document.getSelection();

}

else if (document.selection)>

{

txt = document.selection.createRange().text;

}

else>

{

alert( 'selection not supported');>

}

document.getElementById( '<%=hidSelectedText.ClientID %>').value = txt;>

}

</script>>

</div>>

</form>>

-----------------------------------------------------------------------

protected void showselected_Click(object sender, EventArgs e)>

{

Response.Write(hidSelectedText.Value);

}

how to navigate in solution explorer on selecting open file.

Sandeep Bhutani — Wed, 13 Aug 2008 04:57:41 GMT

Go to

Tools > Options

Expand "Projects And Solutions"

Check "Track Active item in Solution Explorer"

How can I encode a URL in dotnet

Sandeep Bhutani — Fri, 01 Aug 2008 13:50:01 GMT

Use

Server.UrlEncode

Difference between an abstract method & virtual method

Raj Shekhar — Fri, 01 Aug 2008 11:02:21 GMT

Virtual method has an implementation & provide the derived class with the option of overriding it.

Abstract method does not provide an implementation & forces the derived class to override the method.

What connections does Microsoft SQL Server support and which one trusted?

Raj Shekhar — Fri, 01 Aug 2008 10:53:44 GMT

Windows Authentication (via Active Directory) and SQL Server authentication (via Microsoft SQL Server username and password).

Windows Authentication is trusted because the username and password are checked with the Active Directory,

the SQL Server authentication is untrusted, since SQL Server is the only verifier participating in the transaction.

What are three test cases you should go through in unit testing?

Raj Shekhar — Fri, 01 Aug 2008 10:50:06 GMT

1. Positive test cases (correct data, correct output).

2. Negative test cases (broken or missing data, proper handling).

3. Exception test cases (exceptions are thrown and caught properly).

How to open Excel, Word and HTML file in C#?.

Raj Shekhar — Fri, 01 Aug 2008 09:48:11 GMT

System.Diagnostics. Process objDocProcess = new System.Diagnostics.Process();>

objDocProcess.EnableRaisingEvents = false;>

objDocProcess.StartInfo.FileName = @"C:\Excel.xls";>

objDocProcess.Start();

What's the difference between String and String Builder?.

Raj Shekhar — Fri, 01 Aug 2008 06:10:47 GMT

A string is a sequential collection of Unicode characters that is used to represent text. At the other hand the string builder is sealed class(Cannot be inherited)it represents a mutable string of characters.

String is mutable that means that it can't be modified once created, to modify a given string by appending new characters or so the CLR destroy the first string instance and create a new string one and this costs in terms of memory and time process.

Using the string builder, you create a mutable object that recieves modification without having to be destroyed and reinstanciated for each modifiaction

What is Polymorphism?.

Raj Shekhar — Thu, 31 Jul 2008 14:05:28 GMT

Poly means many and morph means form. Thus, polymorphism refers to being able to use many forms of a type without regard to the details.

Polymorphism have 2 types :

1. Compile time also called overloading have 3 types.

· Constructor overloading (i.e., with same constructor name and different no of arguments or different datat types or both )

· Function overloading (i.e., with same function name and different no of arguments or different data types or both)

· operator overloading: example : Variable++;

2 Run time

· It is achieved by overriding parent class method:

Page Life Cycle of ASP.NET

Raj Shekhar — Thu, 31 Jul 2008 13:47:47 GMT

1. OnInit (Init) -- Inializes all Child controls on the Page

2. LoadControlState -- Loads the Control State

3. LoadViewState -- Loads the View State

4. LoadPostData -- Control properties are set according to the received form data

5. Load -- Actions can be performed on the controls as all the pre-activities are complete by this time

6. RaisePostDataChangedEvent -- This event is raised if data has been changed in previous and Current Postbacks.

7. RaisePostBackEvent -- This event handles the user action that caused the Postback.

8. PreRender (OnPreRender) -- This event takes place between postback and saving viewstate. Till this stage changes will be saved to the control.

9. SaveControlState -- Self Explanatory

10. SaveViewState -- Self Explanatory

11. Render -- Generates artifacts at Client side (HTML,DHTML,Scripts) to properly display controls

12. Dispose -- Releases unmanaged Resource ( Database connections, file handles)

13. Unload -- Releases managed Resources ( Instances created by CLR)

Comparision between XmlSerializer, SoapFormatter and BinaryFormatter.

Raj Shekhar — Thu, 31 Jul 2008 13:43:06 GMT

The XmlSerializer can be used when you need the data in the object to be stored in an XML Format. However, this serialize has the limitation that it can serialize only the public fields of an object.

The SoapFormatter is ideal in scenarios where you need interoperability. This is ideal in applications spanning heterogeneous environments.

The BinaryFormatter generates a very compact stream when an object is serialized as compared to the other two techniques and hence is useful when data needs to travel electronically across the wire. This is appropriate when the applications do not involve heterogeneous environments.

What is shallow serialization and deep serialization?.

Raj Shekhar — Thu, 31 Jul 2008 13:40:04 GMT

Serialization is the process of saving the state of an object by converting it to a stream of bytes. The object can then be persisted to file, database, or even memory. The reverse process of serialization is known as deserialization

This classification arises from the format in which the data in the object is persisted. Each of the serialization techniques mentioned have different capabilities and each excel in specific scenarios. The XML serialization technique can convert only the public properties and fields of an object into an XML format. The XML serialization is also known as shallow serialization.

This inability of the XMLSerializer to serialize the private fields of an object is overcome by the SOAP and binary serialization techniques. In the binary and SOAP serialization techniques, the state of the entire object is serialized into a stream of bytes. In cases where the object contains a reference to other objects, even those are serialized. This type of serialization is known as deep serialization.

What’s the difference between an interface and abstract class?

Raj Shekhar — Thu, 31 Jul 2008 12:28:18 GMT

An abstract class may contain complete or incomplete methods. Interfaces can contain only the signature of a method but no body. Thus an abstract class can implement methods but an interface can not implement methods.

An abstract class can contain fields, constructors, or destructors and implement properties. An interface can not contain fields, constructors, or destructors and it has only the property's signature but no implementation.

An abstract class cannot support multiple inheritances, but an interface can support multiple inheritances. Thus a class may inherit several interfaces but only one abstract class.

A class implementing an interface has to implement all the methods of the interface, but the same is not required in the case of an abstract Class.

Various access modifiers such as abstract, protected, internal, public, virtual, etc. are useful in abstract Classes but not in interfaces.

Is it possible to prevent a browser from caching an ASPX page?

Raj Shekhar — Tue, 01 Jul 2008 11:24:24 GMT

You bet. Just call SetNoStore on the HttpCachePolicy object exposed through the Response object's Cache property, as demonstrated here:


	<%@ Page Language="C#" %> <html> <body> <% Response.Cache.SetNoStore (); Response.Write (DateTime.Now.ToLongTimeString ()); %> </body> </html>

SetNoStore works by returning a Cache-Control: private, no-store header in the HTTP response. In this example, it prevents caching of a Web page that shows the current time.

How do I create an ASPX page that periodically refreshes itself?

Raj Shekhar — Tue, 01 Jul 2008 11:08:25 GMT

Most browsers recognize the following META tag as a signal to automatically refresh the page every nn seconds:


	<meta http-equiv="Refresh" content="nn">

Here's an ASPX file that displays the current time of day. Once displayed, it automatically refreshes every 5 seconds:


	<% Page Language="C#" %> <meta http-equiv="Refresh" content="5"> <html> <body> <% Response.Write (DateTime.Now.ToLongTimeString ()); %> </body> </html> >>

How do we upload files to Web pages in ASP.NET?

Raj Shekhar — Tue, 01 Jul 2008 11:02:22 GMT

Use the HtmlInputFile class, which you can declare an instance of with an <input type="file" runat="server"/> tag. The following example is a complete ASPX file that lets a user upload an image file and a comment descibing the image. The Upload_Click method writes the image and the comment to a table named Pictures in a SQL Server database named MyPictures.

< form id="Form2" enctype="multipart/form-data" runat="server">
<table>
<tr>
<td>File name</td>
<td><input type="file" id="Upload" runat="server" /></td>
</tr>
<tr>
<td>Comment</td>
<td><asp:TextBox ID="Comment" RunAt="server" /></td>
</tr>
<tr>
<td></td>
<td><asp:Button Text="Upload" OnClick="Upload_Click(" RunAt="server" /></td>
</tr>
</table>
</form>>

protected void Upload_Click(object sender, EventArgs e)
{
// Create a byte[] from the input file>

int len = Upload.PostedFile.ContentLength;>

byte[] pic = new byte[len];>

Upload.PostedFile.InputStream.Read(pic, 0, len);

// Insert the image and comment into the database>

SqlConnection connection = new SqlConnection("server=localhost;database=mypictures;uid=sa;pwd=");>

try>

{

connection.Open();

SqlCommand cmd = new SqlCommand("insert into Pictures " + "(Picture, Comment) values (@pic, @text)", connection);>

cmd.Parameters.Add( "@pic", pic);>

cmd.Parameters.Add( "@text", Comment.Text);>

cmd.ExecuteNonQuery();

}

finally{
connection.Close();
}
}>