.NET Essentials: Working with LINQ

Course details

Want a simpler, more consistent way to query data ? Language-Integrated Query (LINQ) may be what you're looking for. This general-purpose query toolset allows allows developers to filter, sort, aggregate, and query data directly within C# code. In this course, join Walt Ritscher as he helps you get up and running with LINQ, focusing on LINQ to Objects. Walt begins by showing how to use LINQPad, the code editor and code runner you can use to write and test the LINQ examples provided in this course. He then highlights the key .NET features that power LINQ, the essential elements of a query, and the different types of query expressions. Plus, learn about filters, aggregates, groups, element operations, quantifying data, and partition tools. Along the way, Walt provides challenges that help you grasp how to apply these concepts in the real world.

Concepts

Introduction

Welcome
What you should know
How to access the sample code on GitHub

The Spirit of LINQ

Why build a query engine in a programming language
Explore LINQ essential parts

Work with LINQPad

Why use LINQPad
Initial tour of LINQPad
Set destination folder for course examples
Explore the expression editor
Explore the statements editor
Show formatted output with the Dump method
Explore the program editor
Run a subset of code

Key Parts of .NET

Implicit variable typing
Anonymous types
Object initializers
Collection initializers
Inline code with lambda expressions
Extension methods
More extension methods
Generic types

The Parts of a Query

What sources are queryable
The Enumerable class
Learn how to use the Enumerable static methods
Learn how to use the Enumerable extension methods
Learn how to use the Query Expression syntax
What sources revisited
Deferred execution - When does the query run
Combine methods with execution pipelines
Combine extension methods and query expressions

Generate

The Empty and DefaultIfEmpty methods
The Repeat method
The Range method

Basics

The three types of query expressions
Review query expression clauses
Examples of three query expressions
The select clause
Learn how to use select to project into another type
Select into anonymous type
Learn how to use expressions with select
Challenge - Write select expressions
Solution - Write select expressions
Index into another sequence

Filtering

The Where method
Learn how to use logical operators with the Where method
Explore the OfType class definitions
The OfType method
Challenge - Filter results with Where
Solution - Filter results with Where

Aggregation

Sum, Average, and other aggregates
Create custom aggregates

Groups and Other Stuff

The GroupBy method
GroupBy query expression
GroupBy with ElementSelector
GroupBy with ResultSelector
Iterate over groups
Combine two sequences
Flatten sequence with SelectMany
Challenge - Group results by color values
Solution - Group results by color values

Element Operations

First and Last methods
The FirstOrDefault method
The ElementAt method
Single and SingleOrDefault methods

Set Operations

The Distinct method
The Intersect method
The Union method
The Except method
Find duplicate values

Quantify Data

Learn how to use the Any method to detect empty sequence
Learn how to use Any method to determine if element exists
The Contains method
The All method

Partition

Skip and Take methods
Conditional Skip and Take methods

Other

Learn how to use LINQ in a .NET application
Learn how to use MoreLinq for extended query syntax
Additional MoreLinq examples

Continue Your Journey

Next steps