Delete Duplicate Data through single select query.

with t as
(
select * , row_number() over (partition by empid order by empid) as rank from emp
)
delete from t where rank>1

XML Nodes by Name

//Xml

Names>
name>
firstname>John
lastname>Smith
/Name>
name>
firstname>James
lastname>White
/Name>
/Names>

//C#

XmlDocument xml = new XmlDocument();
xml.Load(myXmlString); // suppose that myXmlString contains "..."

XmlNodeList xnList = xml.SelectNodes("/Names/Name");
foreach (XmlNode xn in xnList)
{
string firstName = xn["FirstName"].InnerText;
string lastName = xn["LastName"].InnerText;
Console.WriteLine("Name: {0} {1}", firstName, lastName);
}

Transaction in sqlserver

begin tran
begin try
insert into a(id) values('a')
insert into a1 values('sdf','adsf1212121',10012121)
commit tran
print'commit'
end try
begin catch
print'rollback'
rollback tran
end catch

Static Classes

A class can be declared static, indicating that it contains only static members. It is not possible to create instances of a static class using the new keyword. Static classes are loaded automatically by the .NET Framework common language runtime (CLR) when the program or namespace containing the class is loaded.

Use a static class to contain methods that are not associated with a particular object. For example, it is a common requirement to create a set of methods that do not act on instance data and are not associated to a specific object in your code. You could use a static class to hold those methods.

The main features of a static class are:

They only contain static members.

They cannot be instantiated.

They are sealed.

They cannot contain Instance Constructors (C# Programming Guide).

Creating a static class is therefore much the same as creating a class that contains only static members and a private constructor. A private constructor prevents the class from being instantiated.

The advantage of using a static class is that the compiler can check to make sure that no instance members are accidentally added. The compiler will guarantee that instances of this class cannot be created.

Static classes are sealed and therefore cannot be inherited. Static classes cannot contain a constructor, although it is still possible to declare a static constructor to assign initial values or set up some static state.

STUFF vs REPLACE in Asp.net

STUFF - Deletes a specified length of characters and inserts another set of characters at a specified starting point.
SELECT STUFF('abcdef', 2, 3, 'ijklmn')
GO
Here is the result set:
---------
aijklmnef
REPLACE - Replaces all occurrences of the second given string expression in the first string expression with a third expression.
SELECT REPLACE('abcdefghicde','cde','xxx')
GO
Here is the result set:
------------
abxxxfghixxx

DDL, DML, DCL and TCL Commands

DML

DML is abbreviation of Data Manipulation Language. It is used to retrieve, store, modify, delete, insert and update data in database.

SELECT – Retrieves data from a table
INSERT - Inserts data into a table
UPDATE – Updates existing data into a table
DELETE – Deletes all records from a table

DDL

DDL is abbreviation of Data Definition Language. It is used to create and modify the structure of database objects in database.

CREATE – Creates objects in the database
ALTER – Alters objects of the database
DROP – Deletes objects of the database
TRUNCATE – Deletes all records from a table and resets table identity to initial value.

DCL

DCL is abbreviation of Data Control Language. It is used to create roles, permissions, and referential integrity as well it is used to control access to database by securing it.

GRANT – Gives user’s access privileges to database
REVOKE – Withdraws user’s access privileges to database given with the GRANT command

TCL

TCL is abbreviation of Transactional Control Language. It is used to manage different transactions occurring within a database.

COMMIT – Saves work done in transactions
ROLLBACK – Restores database to original state since the last COMMIT command in transactions
SAVE TRANSACTION – Sets a savepoint within a transaction

Get Vs Post Method

Get Vs Post Method to send data to the server

Get and Post are methods used to send data to the server:
With the Get method, the browser appends the data onto
the URL. With the Post method, the data is sent
as "standard input."

Use GET:
- during development for debugging purposes (although in ASP.NET it's
also easy to see what has been sent through POST).
- if you want your visitors to be able to bookmark the submitted pages
- if you want to refer to submitted pages using hyperlinks

Use POST:
- for forms with password fields
- for large forms or forms with large text fields

Please note that web forms in ASP.NET use POST by default.

It can be changed into GET, but only for small forms. Web forms can post a lot
of data, especially when ViewState is involved.