Daily Archives: August 1, 2010

Find SQL last inserted row without using INDEX / Identity / TimeStamp Column

01 Sunday Aug 2010

Posted by in SQL Concepts, T SQL Puzzles

≈ 3 Comments

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You can get LAST ROW without using INDEX or IDENTITY COLUMN or TIMESTAMP COLUMN

— FIND OUT LAST INSERTED ROW WITHOUT USING INDEX / IDENTITY COLUMN / TIME STAMP COLUMN 


–-Create a table 
CREATE TABLE TestLastQuery
( 
 Name varchar(50),
 Address varchar(70) 
)
GO

  
-–Insert the values

INSERT INTO TestLastQuery ( Name , Address )
VALUES ( 'Pawan' , 'Pune ') 

INSERT INTO TestLastQuery ( Name , Address )
VALUES ( 'Gauri' , 'A Nagar ') 

INSERT INTO TestLastQuery ( Name , Address )
VALUES ( 'Saurabh' , 'A Nagar ') 

INSERT INTO TestLastQuery ( Name , Address )
VALUES ( 'Himanshu' , 'Padmavati ') 

INSERT INTO TestLastQuery ( Name , Address )
VALUES ( 'Rahul W' , ' Jordan') 

  
-– Use the below query to find out the last inserted row

SELECT TOP 1 Name , Address , row_number() over ( order by

( SELECT 2 ) ) AS ROWNUMBER FROM TestLastQuery ORDER BY ROWNUMBER

DESC

Pawankkmr@gmail.com , Pawan Kumar

Properties of Interfaces in C#

01 Sunday Aug 2010

Posted by in C#

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Please find important properties of interfaces of c#.

1. An interface cannot be instantiated directly.

2. Interface can contain events , indexers , methods and properties ; or any combination of those given before.

3. Interface contain no implementation of methods.

4. Classes and struct can inherit from more than one interface.

5. An interface can itself inherit from multiple interface.

6. Everything should be public in interfaces.

7. An interface is like an abstract base class , any non abstract type inheriting the interface must implementing all its members.

8. Class has to implement all the methods from interface ; if class is implementing the interface.

9. Interfaces cannot contain fields.

10. An interface an inherit from other interfaces.

I will post some detailed examples on this…

Thanks

Pawan

Pawankkmr@gmail.com

Basics of Delegates

01 Sunday Aug 2010

Posted by in C#

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Delegates :
 
1.They are like function pointers.
2. They are .Net objects which points to an event handler that matches its specific signature. Delegates add a safety dimension in handling function pointers in .Net.
3. They are type safe , object oriented , secure.They can be used to invoke methods of matching signature.
4. It is very much necessary to make sure that the functions which the delegates points has the same number of argument type and same return type.
 
Types of delegates
a) Single Case delegate. Name space used is System.Delegate.
b) MultiCast Delegate : Name space used is System.Multicast Delegate
 
A delegate is called single cast delegate if it invokes a single method. In other words we can say that single cast delegates refer to a single method with matching signature.
 
Muticast delegate : They are nothing but a single cast delegate that can invoke multiple methods of matching signature.It derives from System.MutiCast Delegate class which is a sub class of System.Delegate.
 
Will add one more post of examples in this case.