All set to lanuch ipod in india, a news from midday news
"Apple's iPhone, the touch screen handset that acquired a cult status in the US and other western countries, will be available to Indian mobile users through Bharti Airtel at the stroke of midnight on August 21, giving competitors like Nokia, Samsung and others a run for their money.
Millions of Airtel subscribers will be able to purchase the iPhone at Airtel's Relationship Centres from August 22.
"iPhone has been an iconic technological revelation of this year and Airtel has been at the forefront of innovation and customer delight in the Indian telecom sector," Sanjay Kapoor, President, Bharti Airtel mobile services, said.
iPhone is embedded with all 3G features and is twice as fast as the existing mobile phones. The phone also has in-built GPS system, that facilitates as a navigation and positioning tool.
US-based Apple has tied up with Airtel and Vodafone to bring iPhone in the country.
Asked at what price it will be available, Bharti Airtel officials declined to give details."
To read the whole article....
http://www.mid-day.com/news/2008/aug/06082008-iPhone-in-India-from-Aug-22.htm
Jul 14, 2008
Storing and Retirving Data in XML format from sql server
Retrieving and storing data in XML format in Sql Server 2000.
Let there are A,B,C,D,E,F ……….. controls .
Through String builder as
StringBuilder xmlData = new StringBuilder();
xmlData.Append("<Column>");
xmlData.Append("<ColumnVal ");
xmlData.Append(" A=");
xmlData.Append("'0'");
xmlData.Append(" B=");
xmlData.Append("’1’");
xmlData.Append(" C=");
xmlData.Append(" 2=");
xmlData.Append(" D=");
xmlData.Append(" 3=");
xmlData.Append(" E=");
……………………………………………………………………………………
……………………………………………………………………………………..
……………………………………………………………………………………
xmlData.Append("</Column>");
xmlData.Append("</ColumnVal ");
And at last it will created as :
<Column ColumnVal=1 A=’val_A’ B=’val_B’ C=’val_C’ D=’val_D’ E=’val_E’ F=’val_F’………………….></ Column>
<Column ColumnVal=2 A=’val_A’ B=’val_B’ C=’val_C’ D=’val_D’ E=’val_E’ F=’val_F’………………….></ Column>
<Column ColumnVal=3 A=’val_A’ B=’val_B’ C=’val_C’ D=’val_D’ E=’val_E’ F=’val_F’………………….></ Column>
<Column ColumnVal=4 A=’val_A’ B=’val_B’ C=’val_C’ D=’val_D’ E=’val_E’ F=’val_F’………………….></ Column>
………………………….
………………………….
………………………….
<Column ColumnVal=20 A=’val_A’ B=’val_B’ C=’val_C’ D=’val_D’ E=’val_E’ F=’val_F’………………….></ Column>
send this string into DataBase in as xml datatype.
And write query for inserting into datatable.
insert into YourTableName(A,B,C,D,E,F,G,H,…………………………… ColumnVal)
SELECT A,B,C,D,E,F,G,H, ColumnVal FROM OPENXML (@idoc, '/XML/ Column',1)
Retriving data from database.
It will return data in xml format.
CONVERT(xml,(select * from YourTableName where ‘yourcondition’ for xml raw,Elements,ROOT(' Column '))) as ColumnValue
Jul 7, 2008
Clustered Index vs Non Clustered Index
Clustered Index | Non Clustered Index
Indexing is used to get fast retrival of data. The indexing which is done on physical storage is known as Clustered Indexing. And an indexing which is performed logically is know as Non Clustered Indexing.
Clustered Indexing can be only one per table as we phyisically can arrange in one way only, while a table can have 249 Non Clustered Index.
Indexing should be used on table which not very frequently having update operations on it. There are many ways which can be used to get more performance while retrieving data.
Covering Index is --> when you create an index on fields which you are also using in select query, is know as covering index.
For ex suppose
Employee Table
---------------
EmpID int
EmpName
EmpDept
EmpDesing
----------------
If you have a query which only select EmpID and EmpName, then we can create a non clustered index with these two fields only, and it gains our performance while retrieving data.
Indexing is used to get fast retrival of data. The indexing which is done on physical storage is known as Clustered Indexing. And an indexing which is performed logically is know as Non Clustered Indexing.
Clustered Indexing can be only one per table as we phyisically can arrange in one way only, while a table can have 249 Non Clustered Index.
Indexing should be used on table which not very frequently having update operations on it. There are many ways which can be used to get more performance while retrieving data.
Covering Index is --> when you create an index on fields which you are also using in select query, is know as covering index.
For ex suppose
Employee Table
---------------
EmpID int
EmpName
EmpDept
EmpDesing
----------------
If you have a query which only select EmpID and EmpName, then we can create a non clustered index with these two fields only, and it gains our performance while retrieving data.
Jul 1, 2008
Get all the triggers for a Database
To get all the triggers list and their scripts run the script below. View the result in file view mode.
SELECT [text]
FROM sysobjects o
JOIN syscomments c ON o.id = c.id
WHERE xtype = 'TR'
SELECT [text]
FROM sysobjects o
JOIN syscomments c ON o.id = c.id
WHERE xtype = 'TR'
Getting all stored procedures scripts from a Database
By using Cursor
declare @proc_name varchar(100)
declare @str_query nvarchar(MAX)
declare loop_proc cursor
for select [name] from sys.procedures where type='P'
and is_ms_shipped = 0
open loop_proc
FETCH NEXT FROM loop_proc INTO @proc_name
IF @@FETCH_STATUS <> 0
PRINT ' <>'
WHILE @@FETCH_STATUS = 0
BEGIN
SELECT @str_query = 'sp_helptext ' + @proc_name
PRINT @str_query
exec sp_executesql @str_query
FETCH NEXT FROM loop_proc INTO @proc_name
END
CLOSE loop_proc
DEALLOCATE loop_proc
Run these sql statements and view the result in Text mode. You will get all scripts for stored procedures.
From sysobjects
This is better option to get all stroed procedures from a database.
SELECT [text]
FROM
sysobjects o
JOIN syscomments c ON o.id = c.id
WHERE xtype = 'P'
declare @proc_name varchar(100)
declare @str_query nvarchar(MAX)
declare loop_proc cursor
for select [name] from sys.procedures where type='P'
and is_ms_shipped = 0
open loop_proc
FETCH NEXT FROM loop_proc INTO @proc_name
IF @@FETCH_STATUS <> 0
PRINT ' <
WHILE @@FETCH_STATUS = 0
BEGIN
SELECT @str_query = 'sp_helptext ' + @proc_name
PRINT @str_query
exec sp_executesql @str_query
FETCH NEXT FROM loop_proc INTO @proc_name
END
CLOSE loop_proc
DEALLOCATE loop_proc
Run these sql statements and view the result in Text mode. You will get all scripts for stored procedures.
From sysobjects
This is better option to get all stroed procedures from a database.
SELECT [text]
FROM
sysobjects o
JOIN syscomments c ON o.id = c.id
WHERE xtype = 'P'
Jun 27, 2008
Abstract Classs vs Virtual Methods
Abstract Class:
Abstract class is a class that has no direct instances, but whose descendants may have direct instances. There are case in which it is useful to define classes for which the programmer never intends to instantiate any objects; because such classes normally are used as bae-classes in inheritance hierarchies, we call such classes abstract classes These classes cannot be used to instantiate objects; because abstract classes are incomplete. Derived classes called concrete classesmust define the missing pieces.
Abstract classes normally contain one or more abstract methods or abstract properties, such methods or properties do not provide implementations, but our derived classes must override inherited abstract methods or properties to enable obejcts ot those derived classes to be instantiated, not to override those methods or properties in derived classes is syntax error, unless the derived class also is an abstract class.
In some cases, abstract classes constitute the top few levels of the hierarchy, for Example abstract class Shape with abstract method Draw() has tow derived abstract classe Shape2D & Shape3D inherites the method Draw() & also do not provide any implementation for it. Now we have normal classes Rectangle, Square & Circle inherites from Shape2D, and another group of classes Sphere, Cylinder & Cube inherites from Shape3D. All classes at the bottom of the hierarchy must override the abstract method Draw().
A class is made abstract by declaring it with Keyword abstract.
Example:
public abstract class Shape
{
//...Class implementation
public abstract void Draw(int x, int y)
{
//this method mustn't be implemented here.
//If we do implement it, the result is a Syntax Error.
}
}
public abstract class Shape2D : Shape
{
//...Class implementation
//...you do not have to implement the the method Draw(int x, int y)
}
public class Cricle : Shape2D
{
//here we should provide an implemetation for Draw(int x, int y)
public override void Draw(int x, int y)
{
//draw the shape
}
}
Difference between an abstract method & virtual method:
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.
Important Notes:
(a)Any Class with abstract method or property in it must be declared abstract
(b)Attempting to instantiate an object of an abstract class retults in a compilation error
Example:
Shape m_MyShape = new Shape(); //it is Wrong to that.
But we can do that.
Shape m_MyShape = new Circle(); // True
Or
Shape m_MyShape;
/*
declare refrences only, and the refrences can refer to intances of
any concrete classes derived from abstract class
*/
Circle m_MyCircle = new Circle();
m_MyShape = m_MyCircle; // Also True
(d)An abstract class can have instance data and non-abstract methods -including constructors-.
Abstract class is a class that has no direct instances, but whose descendants may have direct instances. There are case in which it is useful to define classes for which the programmer never intends to instantiate any objects; because such classes normally are used as bae-classes in inheritance hierarchies, we call such classes abstract classes These classes cannot be used to instantiate objects; because abstract classes are incomplete. Derived classes called concrete classesmust define the missing pieces.
Abstract classes normally contain one or more abstract methods or abstract properties, such methods or properties do not provide implementations, but our derived classes must override inherited abstract methods or properties to enable obejcts ot those derived classes to be instantiated, not to override those methods or properties in derived classes is syntax error, unless the derived class also is an abstract class.
In some cases, abstract classes constitute the top few levels of the hierarchy, for Example abstract class Shape with abstract method Draw() has tow derived abstract classe Shape2D & Shape3D inherites the method Draw() & also do not provide any implementation for it. Now we have normal classes Rectangle, Square & Circle inherites from Shape2D, and another group of classes Sphere, Cylinder & Cube inherites from Shape3D. All classes at the bottom of the hierarchy must override the abstract method Draw().
A class is made abstract by declaring it with Keyword abstract.
Example:
public abstract class Shape
{
//...Class implementation
public abstract void Draw(int x, int y)
{
//this method mustn't be implemented here.
//If we do implement it, the result is a Syntax Error.
}
}
public abstract class Shape2D : Shape
{
//...Class implementation
//...you do not have to implement the the method Draw(int x, int y)
}
public class Cricle : Shape2D
{
//here we should provide an implemetation for Draw(int x, int y)
public override void Draw(int x, int y)
{
//draw the shape
}
}
Difference between an abstract method & virtual method:
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.
Important Notes:
(a)Any Class with abstract method or property in it must be declared abstract
(b)Attempting to instantiate an object of an abstract class retults in a compilation error
Example:
Shape m_MyShape = new Shape(); //it is Wrong to that.
But we can do that.
Shape m_MyShape = new Circle(); // True
Or
Shape m_MyShape;
/*
declare refrences only, and the refrences can refer to intances of
any concrete classes derived from abstract class
*/
Circle m_MyCircle = new Circle();
m_MyShape = m_MyCircle; // Also True
(d)An abstract class can have instance data and non-abstract methods -including constructors-.
Polymorphism, Method Hiding and Overriding in C#
Polymorphism
One of the fundamental concepts of object oriented software development is polymorphism. The term polymorphism (from the Greek meaning "having multiple forms") in OO is the characteristic of being able to assign a different meaning or usage to something in different contexts - specifically, to allow a variable to refer to more than one type of object.
C# Example
Let's assume the following simple classes A and B for the discussions in this text. A is the base class, B is derived from A.
Inherited Methods
A method Foo() which is declared in the base class A and not redeclared in classes B or C is inherited in the two subclasses
using System;
namespace Polymorphism
{
class A
{
public void Foo() { Console.WriteLine("A::Foo()"); }
}
class B : A {}
class Test
{
static void Main(string[] args)
{
A a = new A();
a.Foo(); // output --> "A::Foo()"
B b = new B();
b.Foo(); // output --> "A::Foo()"
}
}
}
The method Foo() can be overridden in classes B and C:
using System;
namespace Polymorphism
{
class A
{
public void Foo() { Console.WriteLine("A::Foo()"); }
}
class B : A
{
public void Foo() { Console.WriteLine("B::Foo()"); }
}
class Test
{
static void Main(string[] args)
{
A a;
B b;
a = new A();
b = new B();
a.Foo(); // output --> "A::Foo()"
b.Foo(); // output --> "B::Foo()"
a = new B();
a.Foo(); // output --> "A::Foo()"
}
}
}
There are two problems with this code.
The output is not really what we, expected. The method Foo() is a non-virtual method. C# requires the use of the keyword virtual in order for a method to actually be virtual.
Although the code compiles and runs, the compiler produces a warning:
...\polymorphism.cs(11,15): warning CS0108: The keyword new is required on 'Polymorphism.B.Foo()' because it hides inherited member 'Polymorphism.A.Foo()'
Virtual and Overridden Methods
Only if a method is declared virtual, derived classes can override this method if they are explicitly declared to override the virtual base class method with the override keyword.
using System;
namespace Polymorphism
{
class A
{
public virtual void Foo() { Console.WriteLine("A::Foo()"); }
}
class B : A
{
public override void Foo() { Console.WriteLine("B::Foo()"); }
}
class Test
{
static void Main(string[] args)
{
A a;
B b;
a = new A();
b = new B();
a.Foo(); // output --> "A::Foo()"
b.Foo(); // output --> "B::Foo()"
a = new B();
a.Foo(); // output --> "B::Foo()"
}
}
}
Method Hiding
Why did the compiler in the second listing generate a warning? Because C# not only supports method overriding, but also method hiding. Simply put, if a method is not overriding the derived method, it is hiding it. A hiding method has to be declared using the new keyword. The correct class definition in the second listing is thus:
using System;
namespace Polymorphism
{
class A
{
public void Foo() { Console.WriteLine("A::Foo()"); }
}
class B : A
{
public new void Foo() { Console.WriteLine("B::Foo()"); }
}
class Test
{
static void Main(string[] args)
{
A a;
B b;
a = new A();
b = new B();
a.Foo(); // output --> "A::Foo()"
b.Foo(); // output --> "B::Foo()"
a = new B();
a.Foo(); // output --> "A::Foo()"
}
}
}
Combining Method Overriding and Hiding
Methods of a derived class can both be virtual and at the same time hide the derived method. In order to declare such a method, both keywords virtual and new have to be used in the method declaration:
class A
{
public void Foo() {}
}
class B : A
{
public virtual new void Foo() {}
}
A class C can now declare a method Foo() that either overrides or hides Foo() from class B:
class C : B
{
public override void Foo() {}
// or
public new void Foo() {}
}
Important things to remember -->
1. If you are using same name in derived class it hides the base class method, and generate a compiler warning. Use new keyword to supress this warning and tells the compiler that ok i am hiding it intentional.
2. Else define the base as virtual and write override in derived class method.
3. If you dont sure whether you want to hide or override use both virtual and new in base class method definition.
One of the fundamental concepts of object oriented software development is polymorphism. The term polymorphism (from the Greek meaning "having multiple forms") in OO is the characteristic of being able to assign a different meaning or usage to something in different contexts - specifically, to allow a variable to refer to more than one type of object.
C# Example
Let's assume the following simple classes A and B for the discussions in this text. A is the base class, B is derived from A.
Inherited Methods
A method Foo() which is declared in the base class A and not redeclared in classes B or C is inherited in the two subclasses
using System;
namespace Polymorphism
{
class A
{
public void Foo() { Console.WriteLine("A::Foo()"); }
}
class B : A {}
class Test
{
static void Main(string[] args)
{
A a = new A();
a.Foo(); // output --> "A::Foo()"
B b = new B();
b.Foo(); // output --> "A::Foo()"
}
}
}
The method Foo() can be overridden in classes B and C:
using System;
namespace Polymorphism
{
class A
{
public void Foo() { Console.WriteLine("A::Foo()"); }
}
class B : A
{
public void Foo() { Console.WriteLine("B::Foo()"); }
}
class Test
{
static void Main(string[] args)
{
A a;
B b;
a = new A();
b = new B();
a.Foo(); // output --> "A::Foo()"
b.Foo(); // output --> "B::Foo()"
a = new B();
a.Foo(); // output --> "A::Foo()"
}
}
}
There are two problems with this code.
The output is not really what we, expected. The method Foo() is a non-virtual method. C# requires the use of the keyword virtual in order for a method to actually be virtual.
Although the code compiles and runs, the compiler produces a warning:
...\polymorphism.cs(11,15): warning CS0108: The keyword new is required on 'Polymorphism.B.Foo()' because it hides inherited member 'Polymorphism.A.Foo()'
Virtual and Overridden Methods
Only if a method is declared virtual, derived classes can override this method if they are explicitly declared to override the virtual base class method with the override keyword.
using System;
namespace Polymorphism
{
class A
{
public virtual void Foo() { Console.WriteLine("A::Foo()"); }
}
class B : A
{
public override void Foo() { Console.WriteLine("B::Foo()"); }
}
class Test
{
static void Main(string[] args)
{
A a;
B b;
a = new A();
b = new B();
a.Foo(); // output --> "A::Foo()"
b.Foo(); // output --> "B::Foo()"
a = new B();
a.Foo(); // output --> "B::Foo()"
}
}
}
Method Hiding
Why did the compiler in the second listing generate a warning? Because C# not only supports method overriding, but also method hiding. Simply put, if a method is not overriding the derived method, it is hiding it. A hiding method has to be declared using the new keyword. The correct class definition in the second listing is thus:
using System;
namespace Polymorphism
{
class A
{
public void Foo() { Console.WriteLine("A::Foo()"); }
}
class B : A
{
public new void Foo() { Console.WriteLine("B::Foo()"); }
}
class Test
{
static void Main(string[] args)
{
A a;
B b;
a = new A();
b = new B();
a.Foo(); // output --> "A::Foo()"
b.Foo(); // output --> "B::Foo()"
a = new B();
a.Foo(); // output --> "A::Foo()"
}
}
}
Combining Method Overriding and Hiding
Methods of a derived class can both be virtual and at the same time hide the derived method. In order to declare such a method, both keywords virtual and new have to be used in the method declaration:
class A
{
public void Foo() {}
}
class B : A
{
public virtual new void Foo() {}
}
A class C can now declare a method Foo() that either overrides or hides Foo() from class B:
class C : B
{
public override void Foo() {}
// or
public new void Foo() {}
}
Important things to remember -->
1. If you are using same name in derived class it hides the base class method, and generate a compiler warning. Use new keyword to supress this warning and tells the compiler that ok i am hiding it intentional.
2. Else define the base as virtual and write override in derived class method.
3. If you dont sure whether you want to hide or override use both virtual and new in base class method definition.
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