What is Encapsulation?

Encapsulation means that a group of related properties, methods, and other members treated as a single unit or object. This hides the data from being accessed from outside a class directly, only through the functions inside the class is able to access the information.

What is difference between class and object?

Class is a blue print or some template and object is a building created from this blue print or template. Class is a more abstract definition of something and object is the real thing that belongs to that class.

For example

Class:

class Bike {

       

    }

Object:

Bike myObject = new Bike();

What is an Object in Object Oriented Programming?

Objects are usable instances of classes. Using the blue print analogy, a class is a blueprint and object is building made from that blue print. Classes describe the type of objects.

For example we have a class (say Bike)

class Bike {

       

    }

Then we create object of this class as

Bike myObject = new Bike();

Objects share two characteristic. They have state and behavior. An object stores its state in fields (variables) and exposes its behavior through methods.

Software objects are conceptually similar to real world objects. For example we have real world object Dog.

Dog has state name, color, breed, hungry and behavior barking, fetching, wagging tail etc.

We represent it in software world as

class Dog

    {

        string name;

        string color;

        string breed;

        string hungry;

        void Barking()

        {  

            // function definition

        }

        void Fetching()

        {

            // function definition

        }

        void Waggingtail()

        {

            // function definition

        }

    }

Dog objDog = new Dog();

What is Class?

A class is the blue print from where individual objects are created.  For example in real world, we may find many individual objects of same kind. There may be thousands of bikes in existence, all of the same make and model. Each bike was built from the same set of blueprints and therefore contains the same component. In object oriented terms, we say that our bike is an instance of the class of objects known as bikes.

The following Bike class is one of implementation of a bike.

class Bike {

        int Speed = 0;

        int Gear = 0;

        void SpeedUp(int increment)

        {

            Speed += increment;

        }

        void ApplyBreakes(int decrement)

        {

            Speed -= decrement;

        }

    }

Simple example of class is

class SampleClass {

   

    }

What is Object Oriented Programming?

Object oriented programming is a programming language model organized around objects rather than action, and data rather than logic. Objects have both data fields and associated procedures called methods. Objects are instances of classes and used to interact with one another to design applications and computer programs.

Key Concepts of Entity Data Model

The Entity Data Model (EDM) uses three key concepts to describe the structure of data: entity type, association type, and property. These are the most important concepts in describing the structure of data in any implementation of the EDM.
Entity Type
In a conceptual model, An entity represents a specific object (such as a specific customer or order). Each entity must have a unique entity key within an entity set.
Association
In a conceptual model, an association represents a relationship between two entity types (such as Customer and Order).
Property
Entity types contains properties that define the structure and characteristics of Entities. For example, a Customer entity type may have properties such as CustomerId, Name, and Address.

What are Advantages and Disadvantages of Entity Framework

There are several advantages and disadvantages of using Entity Framework.
Advantages

• No need to write the Data access layer code. Entire Data access layer code will be generated by the Entity  Designer (.edmx file). 
• For small applications, no need to write Stored procedures for the CRUD opeartions (Insert,Update,Delete and modify). The Designer will provide the implementation. Developer need to consume those methods.
• Reduces development effort and Unit Testing effort.

Disadvantages

• As the queries are dynamic there might be a hit in the performance of the application.

What is Microsoft ADO.NET Entity Framework

The Microsoft ADO.NET Entity Framework (EF) is an Object/Relational Mapping (ORM) framework that enables developers to work with relational data as domain-specific objects, eliminating the need for most of the data access plumbing code that developers usually need to write.

The Entity Framework works with Microsoft SQL Server and 3rd party databases through extended ADO.NET Data Providers, providing a common query language against different relational databases through either LINQ to Entities or Entity SQL.

Set and Get Textbox Value inside ascx Control from ASP.NET Page

Setting and getting Textbox value inside user control (ascx control) from aspx page is a usual practice in both simple and complex projects.

In this tutorial, we will

• Create New User Control.
• Add User Control in aspx Page.
• Set Textbox Value inside User Control
• Get Textbox value From User Control

Create New User Control

1. Right Click on Project, Click Add New Item.
2. A pop up window will be opened.
3. Select Web User Control from list, change its Name to 'myControl' and click Add. 
4. Two files will be added with name 'myControl.ascx' and 'myControl.ascx.cs'

Replace the code in 'myControl.ascx' file with following code.

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="myControll.ascx.cs" Inherits="Controls_myControll" %>

<table>

    <tr>

        <td>

            Name :

        </td>

        <td>

            <asp:TextBox ID="txtName" runat="server"></asp:TextBox>

        </td>

    </tr>

    <tr>

        <td>

            Age :

        </td>

        <td>

            <asp:TextBox ID="txtAge" runat="server"></asp:TextBox>

        </td>

    </tr>

    <tr>

        <td>

            Profession :

        </td>

        <td>

            <asp:TextBox ID="txtProfession" runat="server"></asp:TextBox>

        </td>

    </tr>

</table>

Add following code in 'myControl.ascx.cs' File.

    public string Name

    {

        get { return txtName.Text.ToString(); }

        set { txtName.Text = value; }

    }

    public string Age

    {

        get { return txtAge.Text.ToString(); }

        set { txtAge.Text = value; }

    }

    public string Profession

    {

        get { return txtProfession.Text.ToString(); }

        set { txtProfession.Text = value; }

    }

Add User Control in aspx Page

1. Create New aspx Page with name ‘PageForWebControl’.
2. Open Design View and drag and drop user control on it. Some code will be added in 'PageForWebControl.aspx' page automatically. 

Page will look like this.

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="PageForWebControl.aspx.cs" Inherits="PageForWebControl" %>

<%@ Register src="Controls/myControll.ascx" tagname="myControll" tagprefix="uc1" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    <title></title>

</head>

<body>

    <form id="form1" runat="server">

    <div>   

        <uc1:myControll ID="myControll1" runat="server" />   

    </div>

    </form>

</body>

</html>

Set Textbox Value inside User Control

Add following code snippet in Page Load Event of 'PageForWebControl.aspx' page to set Values of Textbox  inside User Control.

// Setting Values in ASCX Control

        myControll1.Name = "Waqas Ali";

        myControll1.Age = "24";

        myControll1.Profession = "Computer Scientist";

Get Textbox value From User Control

Add following code snippet in Page Load Event of PageForWebControl.aspx page to get values of Textbox from User Control.

        string _name = string.Empty;

        int _age = 0;

        string _profession = string.Empty;

// Getting Values from ASCX Control

        _name = myControll1.Name;

        _age = Convert.ToInt32(myControll1.Age);

        _profession = myControll1.Profession;

Now you are all done. Run Project and test your values.

Difference Between string and String in C#.NET

There is no different between string and String (System.String). string is an alias for System.String in C#.Net.

They compile to the same code, so no difference at execution time. The complete list of aliases in C#.Net is

object:System.Object 
string:System.String
bool:System.Boolean
byte:System.Byte
sbyte:System.SByte
short:System.Int16
ushort:System.UInt16
int:System.Int32
uint:System.UInt32
long:System.Int64
ulong:System.UInt64
float:System.Single
double:System.Double
decimal:System.Decimal
char:System.Char

ORA-00254 Error in Archive Control String

Error Code
ORA-00254

Description
Error in archive control string 'string'.

Cause
Possible cause of this error is, the specified archive log location is invalid in the archive command or the LOG_ARCHIVE_DEST initialization parameter.

Action
To fix this issue, check the archive string used to make sure it refers to a valid online device.

reference

ORA-00253 Character Limit String Exceeded by Archive Destination

Error Code
ORA-00253

Description
Character limit string exceeded by archive destination string string.

Cause
Possible cause of this error is, the destination specified by an ALTER SYSTEM ARCHIVE LOG START TO command was too long.

Action
To fix this issue, retry the ALTER SYSTEM command using a string shorter than the limit specified in the error message.

reference

ORA-00252 Log String of Thread String is Empty

Error Code
ORA-00252

Description
Log string of thread string is empty, cannot archive.

Cause
Possible cause of this error is, a log must be used for redo generation before it can be archived. The specified redo log was not been used since it was introduced to the database. However it is possible that instance death during a log switch left the log empty.

Action
To fix this issue, empty logs do not need to be archived. Do not attempt to archive the redo log file.

reference

ORA-00251 LOG_ARCHIVE_DUPLEX_DEST cannot be the Same Destination

Error Code
ORA-00251

Description
LOG_ARCHIVE_DUPLEX_DEST cannot be the same destination as string string.

Cause
Possible cause of this error is, the destination specified by the LOG_ARCHIVE_DUPLEX_DEST parameter is the same as the destination specified by an ALTER SYSTEM ARCHIVE LOG START TO command.

Action
To fix this issue, specify a different destination for parameter LOG_ARCHIVE_DUPLEX_DEST, or specify a different destination with the ALTER SYSTEM command.

reference

ORA-00250 Archiver not Started

Error Code
ORA-00250

Description
Archiver not started.

Cause
Possible cause of this error is, an attempt was made to stop automatic archiving, but the archiver process was not running.

Action
No action required.

reference

ORA-00238 Operation would Reuse a Filename that is Part of the Database

Error Code
ORA-00238

Description
Operation would reuse a filename that is part of the database.

Cause
Possible cause of this error is, the filename supplied as a parameter to the ALTER DATABASE BACKUP CONTROLFILE command or to cfileSetSnapshotName matches the name of a file that is currently part of the database.

Action
To fix this issue, retry the operation with a different filename.

reference

ORA-00237 Snapshot Operation Disallowed Control File Newly Created

Error Code
ORA-00237

Description
Snapshot operation disallowed, control file newly created.

Cause
Possible cause of this error is, an attempt to invoke cfileMakeAndUseSnapshot with a currently mounted control file that was newly created with CREATE CONTROLFILE was made.

Action
To fix this issue, mount a current control file and retry the operation.

reference

ORA-00236 Snapshot Operation Disallowed Mounted Control File is a Backup

Error Code
ORA-00236

Description
Snapshot operation disallowed, mounted control file is a backup.

Cause
Possible cause of this error is, attempting to invoke cfileSetSnapshotName, cfileMakeAndUseSnapshot, or cfileUseSnapshot when the currently mounted control file is a backup control file.

Action
To fix this issue, mount a current control file and retry the operation.

reference

ORA-00235 Control File Fixed Table Inconsistent due to Concurrent Update

Error Code
ORA-00235

Description
Control file fixed table inconsistent due to concurrent update.

Cause
Possible cause of this error is, concurrent update activity on a control file caused a query on a control file fixed table to read inconsistent information.

Action
To fix this issue, retry the operation.

reference

ORA-00234 Error in Identifying or Opening Snapshot or Copy Control File

Error Code
ORA-00234

Description
Error in identifying or opening snapshot or copy control file

Cause
Possible cause of this error is, a snapshot or copy control file of the specified name could not be found or opened during an invocation of cfileUseSnapshot, cfileMakeAndUseSnapshot, or cfileUseCopy.

Action
To fix this issue, re-create the snapshot or copy control file using cfileMakeAndUseSnapshot or ALTER DATABASE BACKUP CONTROLFILE, respectively.

reference

ORA-00233 Copy Control File is Corrupt or Unreadable

Error Code
ORA-00233

Description
Copy control file is corrupt or unreadable.

Cause
Possible cause of this error is, the specified copy control file was found to be corrupt or unreadable during an invocation of cfileUseCopy.

Action
To fix this issue, before retrying cfileUseCopy, use the ALTER DATABASE BACKUP CONTROLFILE command and specify the same filename that was specified for cfileUseCopy.

reference

ORA-00232 Snapshot Control File is Nonexistent Corrupt or Unreadable

Error Code
ORA-00232

Description
Snapshot control file is nonexistent, corrupt, or unreadable.

Cause
Possible cause of this error is, the snapshot control file was found to be nonexistent, corrupt, or unreadable during an invocation of cfileUseSnapshot.

Action
To fix this issue, call cfileMakeAndUseSnapshot again or for the first time.

reference

ORA-00231 Snapshot Control File has not been Named

ErrorCode
ORA-00231

Description
Snapshot control file has not been named.

Cause
Possible cause of this error is, during an invocation of cfileMakeAndUseSnapshot or cfileUseSnapshot it was detected that no filename for the snapshot control file had previously been specified.

Action
To fix this issue, specify a name for the snapshot control file by calling cfileSetSnapshotName.

reference

ORA-00230 Operation Disallowed Snapshot Control File Enqueue Unavailable

Error Code
ORA-00230

Description
Operation disallowed, snapshot control file enqueue unavailable.

Cause
Possible cause of this error is, the attempted operation cannot be executed at this time because another process currently holds the snapshot control file enqueue.

Action
To fix this issue, retry the operation after the concurrent operation that is holding the snapshot control file enqueue terminates.

reference

ORA-00229 Operation Disallowed Already Hold Snapshot Control File Enqueue

Error Code
ORA-00229

Description
Operation disallowed already hold snapshot control file enqueue.

Cause
Possible cause of this error is, the attempted operation cannot be executed at this time because this process currently holds the snapshot control file enqueue.

Action
To fix this issue, retry the operation after calling cfileUseCurrent to release the snapshot control file enqueue.

reference

ORA-00228 Length of Alternate Control File Name Exceeds Maximum of String

Error Code
ORA-00228

Description
Length of alternate control file name exceeds maximum of string.

Cause
Possible cause of this error is, the specified filename, which was supplied as a parameter to cfileSetSnapshotName or cfileUseCopy, exceeds the maximum filename length for this operating system.

Action
To fix this issue, retry the operation with a shorter filename.

reference

ORA-00227 Corrupt Block Detected in Control File

Error Code
ORA-00227

Description
Corrupt block detected in control file: (block string, # blocks string).

Cause
Possible cause of this error is, a block header corruption or checksum error was detected on reading the control file.

Action
To fix this issue, use the CREATE CONTROLFILE or RECOVER DATABASE USING BACKUP CONTROLFILE command.

reference

ORA-00226 Operation Disallowed while Alternate Control File Open

Error Code
ORA-00226

Description
Operation disallowed while alternate control file open.

Cause
Possible cause of this error is, the attempted operation could not be executed at this time because this process had an alternate control file open for fixed table access.

Action
To fix this issue, retry the operation after calling cfileUseCurrent.

reference

ORA-00225 Expected Size String of Control File Differs from Actual Size String

Error Code
ORA-00225

Description
Expected size string of control file differs from actual size string

Cause
Possible cause of this error is, the expected size of the control file as stored in its header was different than the actual operating system file size. This usually indicates that the control file was corrupted.

Action
To fix this issue, restore a good copy of the control file.

reference

ORA-00224 Control File Resize Attempted with illegal Record Type

Error Code
ORA-00224

Description
Control file resize attempted with illegal record type (string).

Cause
Possible cause of this error is, an attempt was made to expand or shrink the control file by calling cfileResizeSection using an invalid value for the RECORD_TYPE parameter.

Action
To fix this issue, use a value for the RECORD_TYPE parameter that specifies a valid record type other than type 0 (valid range is 1-16).

reference

ORA-00223 Convert File is Invalid or Incorrect Version

Error Code
ORA-00223

Description
Convert file is invalid or incorrect version

Cause
Possible cause of this error is, an Oracle7 to Oracle8 convert file contains invalid data or was created with an different version of the migration utility. This error can also be caused by incorrect ORACLE_HOME environment variable when ALTER DATABASE CONVERT command is issued.

Action
To fix this issue, use a correct version of the convert file or regenerate it with the migration utility. Make sure that the migration utility is the same version as the Oracle8 RDBMS executable and that the ORACLE_HOME environment variable is properly set.

reference

ORA-00222 Operation would Reuse Name of a Currently Mounted control file

Error Code
ORA-00222

Description
Operation would reuse name of a currently mounted control file

Cause
Possible cause of this error is, the filename supplied as a parameter to the ALTER DATABASE BACKUP CONTROLFILE command or to cfileSetSnapshotName matches the name of the specified currently mounted control file.

Action
To fix this issue, Retry the operation with a different filename.

reference

ORA-00221 Error on Write to Control File

Error Code
ORA-00221

Description
Error on write to control file

Cause
Possible cause of this error is, an error occurred when writing to one or more of the control files.

Action
To fix this issue, see accompanying messages.

reference

ORA-00220 Control File not Mounted by First Instance

Error Code
ORA-00220

Description
Control File not mounted by first instance, check alert log for more info

Cause
Possible cause of this error is, the specified control file has a different mount ID than the other control files that are being mounted. This means that the first instance to mount the database did not use this control file.

Action
To fix this issue, find and install the correct control file.

reference

ORA-00219 Required Control File Size Exceeds Maximum Allowable Size

Error Code
ORA-00219

Description
Required control file size (string logical blocks) exceeds maximum allowable size (string logical blocks).

Cause
Possible cause of this error is, an invocation of CREATE DATABASE or CREATE CONTROLFILE was executed specifying a combination of parameters that would require the control file size in blocks to exceed the maximum allowable value.

Action
To fix this issue, in the case of CREATE DATABASE or CREATE CONTROLFILE, use a different combination of MAXDATAFILES, MAXLOGFILES, MAXLOGMEMBERS, MAXLOGHISTORY, and MAXINSTANCES clauses.

reference

ORA-00218 Block Size String of Control File 'string' does not match DB_BLOCK_SIZE

Error Code
ORA-00218

Description
Block size string of control file 'string' does not match DB_BLOCK_SIZE (string)

Cause
Possible cause of this error is, the block size as stored in the control file header is different from the value of the initialization parameter DB_BLOCK_SIZE. This might be due to an incorrect setting of DB_BLOCK_SIZE, or else might indicate that the control file has either been corrupted or belongs to a different database.

Action
To fix this issue, restore a good copy of the control file. If the control file is known to be clean set the DB_BLOCK_SIZE to match control file headers block size value.

reference

ORA-00217 Control File could not be Resized for New Record Types

Error Code
ORA-00217

Description
Control file could not be resized for new record types

Cause
Possible cause of this error is, the control file was missing some new record types supported by this release. These record types are automatically added by resizing the contol file during mount. The resize has failed.

Action
To fix this issue, look in the alert log for the reason that the resize has failed. If indicated in the alert log, give the control file more space. Otherwise, use the CREATE CONTROLFILE script dumped to the trace file to create a new control file.

reference

ORA-00216 Control File could not be Resized for Migration

Error Code
ORA-00216

Description
Control file could not be resized for migration from 8.0.2

Cause
Possible cause of this error is, the control file created by release 8.0.2 was missing some record types. These record types are automatically added by resizing the control file during mount. The resize has failed.

Action
To fix this issue, look in the alert log for the reason that the resize has failed. If indicated in the alert log, give the control file more space. Otherwise, use the CREATE CONTROLFILE script dumped to the trace file to create a new control file.

reference

How to Enable and Disable ASP.NET TextBox Control on CheckBox Click in Java Script

• Create New Project in Visual Studio 2010 (or in any version).
• Add New Page ( named default.aspx ).
• Add Following aspx Code in default.aspx page.

        <table style="width: 100%;">

            <tr>

                <td align="right" style="width: 50%">

                    <asp:Label ID="LabelClick" runat="server" Text="Click Me !!!"></asp:Label>

                </td>

                <td align="left" style="width: 50%;">

                    <asp:CheckBox ID="CheckBox" onclick="EnableDisableTextBox();" Checked="false" runat="server" />

                </td>

            </tr>

            <tr>

                <td align="right" style="width: 50%">

                    <asp:Label ID="LabelName" runat="server" Text="Name:"></asp:Label>

                </td>

                <td align="left" style="width: 50%">

                    <asp:TextBox ID="TextBoxName" runat="server" Width="70%"></asp:TextBox>

                </td>

            </tr>

            <tr>

                <td align="right" style="width: 50%">

                    <asp:Label ID="LabelAge" runat="server" Text="Age:"></asp:Label>

                </td>

                <td align="left" style="width: 50%">

                    <asp:TextBox ID="TextBoxAge" runat="server" Width="70%"></asp:TextBox>

                </td>

            </tr>

        </table>

• Add Following Java Script Code inside head tag in default.aspx page.

    <script type="text/javascript" language="javascript">

        function EnableDisableTextBox() {

            var CallerCheckBoxID = "<%= CheckBox.ClientID %>";

            var LblName = "<%= LabelName.ClientID %>";

            var TxtName = "<%= TextBoxName.ClientID %>";

            var LblAge = "<%= LabelAge.ClientID %>";

            var TxtAge = "<%= TextBoxAge.ClientID %>";

            if (document.getElementById(CallerCheckBoxID).checked == true) {

                document.getElementById(LblName).disabled = true;

                document.getElementById(TxtName).disabled = true;

                document.getElementById(LblAge).disabled = true;

                document.getElementById(TxtAge).disabled = true;

            }

            else {

                document.getElementById(LblName).disabled = false;

                document.getElementById(TxtName).disabled = false;

                document.getElementById(LblAge).disabled = false;

                document.getElementById(TxtAge).disabled = false;

            }

        }

    </script>

You have all done. View it in browser.
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