Daily Archives: August 4, 2010

Properties of Static Constructors

04 Wednesday Aug 2010

Posted by in OOPS

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Some of the properties of Static Constructors are given below. Please add if you know more…

A static constructor does not take access modifiers

A static constructor does not take parameters.

A static constructor is called automatically to initialize the class
before the first instance is created or any static members are
referenced.

A static constructor cannot be called directly.

The user has no control on when the static constructor is executed in the program.

A typical use of static constructors is when the class is using a
log file and the constructor is used to write entries to this file.

Other typical use of static constructor is when the class is using a message box to show the message to the end user.

Developer can directly write classname.method name to access the methods.

Will add some more to complete the static constructors.

What is the difference between Constant Field and a ReadOnly Field in C#?

04 Wednesday Aug 2010

Posted by in C#

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Constant and readonly fields are used to store constant data.

A constant field can only be initialized at the declaration of the
field.This means this can be initialized at the time of development
andby programmer only.

A readonly field can be initialized either at the declaration or in
a constructor. Hence , readonly fields can have different values
depending on the constructor used.

Example is given below :-

readonly int readonlyfield;
public X()
{
readonlyfield = 1;
}

public X(string s)
{
readonlyfield = 5;
}

public X(string s, int i)
{
readonlyfield = i;
}

Constant field is a compile-time constant, the readonly field can be used for runtime constants.

FIND NO OF COLUMNS IN A TABLE – SQL SERVER 2005

04 Wednesday Aug 2010

Posted by in SQL Concepts

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– Create a table
CREATE TABLE Employee
(

Name varchar(50) NOT NULL,
Salary int NOT NULL

)

– Insert the values
INSERT INTO Employee(Name, Salary)
VALUES (‘e5′, 45000)

INSERT INTO Employee(Name, Salary)
VALUES (‘e3′,  30000)

INSERT INTO Employee( Name, Salary )
VALUES (‘e2′,  49000)

INSERT INTO Employee( Name, Salary )
VALUES (‘e4′,  36600)

INSERT INTO Employee( Name, Salary )
VALUES (‘e1′  ,  58000)

SELECT * FROM Employee

–Following queries will help you in finding the no of columns in a table
SELECT COUNT(*) NoOfColumns FROM Syscolumns where id = object_id(‘Employee’)

SELECT COUNT(*) NoOfColumns FROM Syscolumns where id = ( SELECT id from sysobjects  where name = ‘Employee’ )

SELECT COUNT(*) NoOfColumns FROM Information_Schema.[Columns] where table_name = ‘Employee’

–Happy Programming. Share Knowledge.

Pawan Kumar

Pawankkmr@hotmail.com

CAST / CONVERT Difference IN SQL SERVER 2005

04 Wednesday Aug 2010

Posted by in SQL Concepts

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CAST / CONVERT IN SQL SERVER 2005

Both cast and convert perform data type conversions for us.

They both do the same thing with the exception that convert does some date formatting conversions that cast does not offer.

CAST is ANSI complaint.

CONVERT is not ANSI Complaint.

Syntax:

CAST ( Expression as DATATYPE )

CONVERT ( DATATYPE , Expression , Style )

-Pawan Kumar
Pawankkmr@hotmail.com