LINQ Tutorial - For Beginners & Professionals

Understanding LINQ Standard Query Operators

LINQ standard query operators are the methods which help you to write LINQ query. Most of these query methods operate on sequences or collection whose implement the IEnumerable<T> interface or the IQueryable<T> interface. These operators provide query capabilities including filtering, projection, aggregation, sorting and much more.

 

Difference between ADO.NET and LINQ to SQL

As you know LINQ provides a common query syntax to query any data source and ADO.NET allows you to execute query against any RDBMS like SQL Server, Oracle etc. In this article, I am sharing my view on LINQ and ADO.NET.

 

LINQ Inner Join with AND and OR condition

LINQ has a JOIN query operator that provides SQL JOIN like behavior and syntax. As you know, Inner join returns only those records or rows that match or exists in both the tables. The simple inner join example is given below:

 

Understanding Single, SingleOrDefault, First and FirstOrDefault

LINQ provides element operators which return a single element or a specific element from a collection. The elements operators are Single, SingleOrDefault, First, FirstOrDefault, Last, LastOrDefault.

 

Different ways to write LINQ query

LINQ provides a uniform programming model (i.e. common query syntax) to query data sources (like SQL databases, XML documents, ADO.NET Datasets, Various Web services and any other objects such as Collections, Generics etc.). LINQ provides you three different ways to write a LINQ query in C# or VB.

 

Difference between Deferred execution and Immediate execution

LINQ provides a common query syntax to query any data source. In a LINQ query, you always work with objects. The object may in-process object or out-process object. Based on objects, LINQ query expression is translated and executed.

 

Difference between Select and SelectMany in LINQ

Select and SelectMany are projection operators. Select operator is used to select value from a collection and SelectMany operator is used to select values from a collection of collection i.e. nested collection.

 

Understanding Expression and Expression Trees

In .NET, Expression is an abstract class which contains static methods and inherited by various types (like ParameterExpression, MethodCallExpression) to create expression tree nodes of specific types. A ParameterExpression represents a named parameter expression and a MethodCallExpression represents a method call.

 

Comparing LINQ with Stored Procedure

LINQ provided you common query syntax to query various data sources like SQL Server, Oracle, DB2, WebServices, XML and Collection etc. LINQ also has full type checking at compile-time and IntelliSense support in Visual Studio, since it used the .NET framework languages like C# and VB.NET.

 

SQL Joins with C# LINQ

There are Different Types of SQL Joins which are used to query data from more than one tables. In this article, I would like to share how joins work in LINQ. LINQ has a JOIN query operator that provide SQL JOIN like behavior and syntax. Let's see how JOIN query operator works for joins. This article will explore the SQL Joins with C# LINQ.

 

Understanding Var and IEnumerable with LINQ

Basically, IEnumerable is an interface that can move forward only over a collection, it can’t move backward and between the items. Var is used to declare implicitly typed local variable means it tells the compiler to figure out the type of the variable at compilation time. A var variable must be initialized at the time of declaration.

 

IEnumerable VS IList

In LINQ to query data from collections, we use IEnumerable and IList for data manipulation.IEnumerable is inherited by IList, hence it has all the features of it and except this, it has its own features. IList has below advantage over IEnumerable.

 

IEnumerable VS IQueryable

In LINQ to query data from database and collections, we use IEnumerable and IQueryable for data manipulation. IEnumerable is inherited by Iqueryable, hence it has all the features of it and except this, it has its own features. Both have its own importance to query data and data manipulation. Let’s see both the fetures and take the advantage of both the fetures

 

Create xml from database using LINQ

XML data is often used to transfer data from one application to another. Since XML is language independent, hence it is a good choice to use xml for transferring data between two different platform applications. In C#, it is easy to make xml from database by using LINQ to SQL and LINQ to XML.

 

Introduction to LINQ

LINQ stands for Language-Integrated Query. Basically LINQ address the current database development model in the context of Object Oriented Programming Model. If some one wants to develop database application on .Net platform the very simple approach he uses ADO.Net. ADO.Net is serving as middle ware in application and provides complete object oriented wrapper around the database SQL.