How to delete one array element from array

i) unset() method


$Array = array("test1","test2","test3","test3");

unset($Array[2]);

ii) array_diff_key() method


$Array = array("test1","test2","test3","test3");

array_pop($Array);

iii) array_splice() method


$Array = array("test1","test2","test3","test3");

array_splice($Array,1,2);

iv) array_diff() method


$Array = array("test1","test2","test3","test3");

array_shift($Array);

Primary key in SQL Server

Primary key is a single field or combination of fields that uniquely defines a record.
None of the fields that are part of the primary key can contain a null value.
A primary key column cannot contain NULL values.
Each table can have only ONE primary key.

We can create a primary key in table with the CREATE TABLE statement.
Syntax

The syntax to create a primary key using the CREATE TABLE statement:

CREATE TABLE table_name
(
  column1 datatype { NULL | NOT NULL } PRIMARY KEY,
  column2 datatype { NULL | NOT NULL },
  ...
 
);

Example :

CREATE TABLE Persons
(
Employee_Id int NOT NULL PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Department varchar(255),
Salary money
)


DROP a PRIMARY KEY Constraint

We can also drop the PRIMARY KEY constraint, using the below example:

ALTER TABLE Employee
DROP CONSTRAINT pk_EmployeeID

How To Set Textbox1 Value Into Formula Field Of Cystal Reports.

As per client requirement he/she want to selected date dispaly on report(Crystal Report).

Solution : 

Step1 : I have create one formula field "mindate" and "maxdate" in crystal report.

Step2 : Create the instance of the reports class and set the texbox value in crystalreportviwer source.

Example : 

I have used as per my code in aspx.cs in code page.

CrystalReportSource1.ReportDocument.DataDefinition.FormulaFields["mindate"].Text = "'" + Search_FromDate.Value.Trim() + "'";
CrystalReportSource1.ReportDocument.DataDefinition.FormulaFields["maxdate"].Text = "'" + Search_ToDate.Value.Trim()+ "'";
CrystalReportViewer1.ReportSource = CrystalReportSource1;

Note ["mindate"] ,["maxdate"] is the formula field name. which provided into crystal reports.

Result: See Below Image

#C# Why Task introduced in C#?

Why Task introduced in C#?

.net framework provides System.Threading.Tasks.Task class to let you create threads and run them asynchronously. Queuing a work item to a thread pool is useful, but there is no way to know when the operation has finished and what the return value is.So that the reason Microsoft introduced the concept of Task.

Task is an object that represents some work that should be done.

Example:

public class Program {

    public static void Main() {

        // use an Action delegate and named method

        Task task1 = new Task(new Action(printMessage));

        // use an anonymous delegate

        Task task2 = new Task(delegate { printMessage() });

        // use a lambda expression and a named method

        Task task3 = new Task(() => printMessage());

        // use a lambda expression and an anonymous method

        Task task4 = new Task(() => { printMessage() });

        task1.Start();

        task2.Start();

        task3.Start();

        task4.Start();

        Console.WriteLine("Main method complete. Press <enter> to finish.");

        Console.ReadLine();

    }

    private static void printMessage() {

        Console.WriteLine("Hello, world!");

    }

}

#C# Ref Parameters vs. Out Parameters in C#

Ref Parameters vs. Out Parameters in C#

Ref: The ref keyword is used to pass an argument as a reference. This means that when value of that parameter is changed in the method, it gets reflected in the calling method. An argument that is passed using a ref keyword must be initialized in the calling method before it is passed to the called method.

Out: The out keyword is used to pass an argument as a reference. This means that when value of that parameter is changed in the method, it gets reflected in the calling method. An argument that is passed using a out keyword not to be initialized in the calling method before it is passed to the called method.

Before calling the method:

[ref]: The caller must set the value of the parameter before passing it to the called method as shown below example int I = 20;

[out]: The caller method is not required to set the value of the argument before calling the method. Most likely, you shouldn't. In fact, any current value is discarded as shown below example int K = 10;

During the call:

[ref]: The called method can read the argument at any time.

[out]: The called method must initialize the parameter before reading it.

Remote calls:

[ref]: The current value is marshaled to the remote call. Extra performance cost.

[out]: Nothing is passed to the remote call. Faster.

Example : class Program

    {

        public static void Main()

        {

            int i = 20;

            int k;

            Display(ref i);  //

            Display2(out k);

            Console.WriteLine("current ref value :" + i);

            Console.WriteLine("current out value :" + k);

            Console.ReadLine();

        }

        public static void Display(ref int i)

        {

            i = 10;

        }

        public static void Display2(out int i)

        {

            i = 10;

        }

    }

Output: Current ref value: 10

            Current out value: 10

#SQL What is the difference between a Clustered and Non Clustered Index?

What is the difference between a Clustered and Non Clustered Index?

1.       One table can only have only one clustered index.
2.       One table can only have many non-clustered indexes.
3.       A clustered index requires no separate storage than the table storage. It forces the rows to be stored sorted on the index key.
4.      A non-clustered index requires separate storage than the table storage to store the index information.
5.      A table with a clustered index is called clustered table. Its rows are stored in a B-Tree structure sorted.
6.      A table without any clustered indexes is called non-clustered table. Its rows are stored in heap structure unsorted.
7.     The default index created as part of the primary key column is a clustered index
8.     The default index created as part of the unique key column is a non-clustered index.
9.       Prior to SQL Server 2008 only 249 Non-clustered Indexes can be created. With SQL Server 2008 and above 999 Non-clustered Indexes can be created

A table can have multiple non-clustered indexes

A table can have multiple non-clustered indexes because they don’t affect the order in which the rows are stored on disk like clustered indexes.

Why can a table have only one clustered index?

Because a clustered index determines the order in which the rows will be stored on disk, having more than one clustered index on one table is impossible. Imagine if we have two clustered indexes on a single table – which index would determine the order in which the rows will be stored? Since the rows of a table can only be sorted to follow just one index, having more than one clustered index is not allowed.

C# What is the difference between IEnumerable and IQueryable?

What is the difference between IEnumerable and IQueryable?

IEnumerable and IQueryable may seem like the same at a quick glance, but there are important differences that us, as developers must be aware so that we not only get a working product out the door but also something that performs well.

IEnumerable	IQueryable
·         IEnumerable exists in the System. Collections namespace.	·         IQueryable exists in the System.Linq Namespace.
·         IEnumerable is suitable for querying data from in-memory collections like List, Array and so on. ·          Example:  IEnumerable<Emp> emp = ent.Emps; IEnumerable<Emp> temp = emp.Where(x => x.Empid ==5).ToList<Emp>(); This where filter is executed on the client side where the “IEnumerable” code is. In other words, all the data is fetched from the database and then at the client it scans and gets the record with “EmpId” is “5”.	·         IQueryable is suitable for querying data from out-memory like remote database collections. ·         Example : In this case, the filter is applied on the database using the “SQL” query. So the client sends a request and on the server side, a select query is fired on the database and only necessary data is returned.
·         IEnumerable not supported Lazy Loading . Hence not suitable for paging like scenarios.	·         IQueryable supported Lazy Loading .
·         While querying data from the database, IEnumerable executes "select query" on the server-side, loads data in-memory on the client-side and then filters the data.	·         While querying data from a database, IQueryable executes a "select query" on server-side with all filters.
·         IEnumerable is beneficial for LINQ to Object and LINQ to XML queries.	·         IQueryable is beneficial for LINQ to SQL queries. ·         IQueryable