c# linq / lambda expressions - … · linq –standard query operators restriction where projection...

C# LINQ / Lambda

Expressions

© Meganadha Reddy K., 2015 http://www.netcomlearning.com/

[Introductory Session]

Meganadha Reddy K.Technical Trainer | NetCom Learning

www.NetComLearning.com

Agenda

• Introduction to Collections: 10 Mins

• Normal way of using loops: 5 Mins

• var keyword : 5 Mins

• LINQ Examples : 20 Mins

• Lambda Expressions : 15 Mins

• Q & A : 5 Mins


This is L100 Webinar on “SQL Server Data Types”

Dot Net Framework


Collections in C#


• Sample Collections:

a. ArrayList

b. Stack

c. Queue

• Sample Generics:

a. List<T>

b. Stack<T>

c. Queue<T>

Demos

Before LINQ


List<int> marks = new List<int>(){30,40,50,60,70,80,20};

foreach(int m in marks){

if(m>50){

Console.WriteLine(m);}

}

Traditional way of writing a for each loop

Queries without LINQ

foreach(Customer c in customers)if (c.Region == "USA") ...

Objects using loops and conditions


Queries without LINQ

//Customers/Customer[@Region='USA']

XML using XPath/XQuery

SELECT * FROM Customers WHERE Region='USA'

SELECT from database tables


Types of LINQ

• LINQ to Objects

• LINQ to SQL

• LINQ to XML

• LINQ to Entities

Our focus for now will be on LINQ to Objects


What is LINQ?


Language INtegrated Query

List<int> marks = newList<int>{30,40,50,60,70,80,20};

var result =from m in markswhere m > 50select m;

var Keyword

LINQ Syntax


from id in source

{ from id in source | where condition }

[ orderby ordering, ordering, … ]

select expr | group expr by key

[ into id query ]

LINQ – Standard Query Operators

Restriction Where

Projection Select, SelectMany

Ordering OrderBy, ThenBy

Grouping GroupBy

Quantifiers Any, All

Partitioning Take, Skip, TakeWhile, SkipWhile

Sets Distinct, Union, Intersect, Except

Elements First, FirstOrDefault, ElementAt

Aggregation Count, Sum, Min, Max, Average

Conversion ToArray, ToList, ToDictionary

Casting OfType<T>


LINQ / Lambda - Demos

Demos


Q & A

?


c# linq / lambda expressions - … · linq –standard query operators restriction where projection...

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