.NET Essentials: Working with LINQ

Learn the basics of working with Language-Integrated Query (LINQ), which allows developers to filter, sort, aggregate, and query data directly within C# code.

Introduction

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

1. The Spirit of LINQ

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

2. 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

3. 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

4. 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

5. Generate

• The Empty and DefaultIfEmpty methods
• The Repeat method
• The Range method

6. 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

7. 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

8. Aggregation

• Sum, Average, and other aggregates
• Create custom aggregates

9. 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

10. Element Operations

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

11. Set Operations

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

12. 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

13. Partition

• Skip and Take methods
• Conditional Skip and Take methods

14. 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