Complete Guide to .NET LINQ: Querying Collections, Databases, and Markup

7h 34mIntermediate2025-05-02

Authors

Walt Ritscher

Programmer, UI Designer, Staff Instructor at LinkedIn Learning

Learn-it Labs

Course details

In this comprehensive course, Walt Ritscher explores the dynamic capabilities of .NET Language Integrated Query (LINQ). Get an introduction to LINQ syntax and versatile operators that streamline data querying, manipulation, and transformation across various sources, such as in-memory objects, databases, and XML files. Discover how to efficiently manage collections with LINQ to Objects, access structured data through LINQ to Entities, and seamlessly navigate hierarchical data with LINQ to XML and LINQ to JSON. Learn advanced techniques like deferred execution and expression trees. Learn how LINQ empowers you to filter, order, group, and aggregate data with ease, ensuring clarity and maintainability in your code. Whether you're working with relational data sources, building data-driven applications, or handling diverse data formats, you'll benefit from mastering the expressive power and convenient integration with C# that LINQ offers.

Skills covered

LINQ.NETDatabase DevelopmentDatabase ManagementSoftware Development ToolsMicrosoftSoftware DevelopmentOne-Off

Concepts

0. Introduction

01 - Unlock the power of in-language queries
02 - How to get the most from this course
03 - Course roadmap - What you ll learn
04 - How to access the sample code on GitHub

1. The Spirit of LINQ

05 - Why LINQ The need for a query engine
06 - LINQ essentials - Key concepts and features
07 - Finding and using the example code

2. Working with LINQPad

08 - Why use LINQPad
09 - Getting started - A tour of LINQPad
10 - How to set LINQPad preferences
11 - Writing and running code in LINQPad
12 - Set a destination folder for course files
13 - How to debug code in LINQPad
14 - Exploring the expression editor
15 - Exploring the statements editor
16 - Format output using the Dump method
17 - Exploring the program editor
18 - How to run a subset of code

3. Quick Looks

19 - Quick look at a LINQ to Objects query
20 - Quick look at a LINQ to Entities query
21 - Quick look at a LINQ to XML query

4. Parts of a LINQ Query

22 - What sources can you query
23 - Introduction to the Enumerable class
24 - Using Enumerable static methods
25 - Using Enumerable extension methods
26 - Writing queries with expression syntax
27 - Revisiting queryable data sources
28 - Deferred execution - When does a query run
29 - Building execution pipelines in LINQ
30 - Mixing extension methods and query syntax

5. Generating Data Sequences

31 - Generating an empty sequence
32 - Using DefaultIfEmpty in LINQ
33 - How to use the Repeat method
34 - How to use the Range method

6. LINQ Basics

35 - The three types of query expressions
36 - Review query expression clauses
37 - Examples of query expressions
38 - Exploring the course .NET class libraries
39 - Querying .NET libraries in ASP.NET
40 - Working with .NET external libraries
41 - Using select to project into an .NET type
42 - Using select to project into an anonymous type
43 - Use expressions with select
44 - Indexing into another sequence
45 - Challenge - Write select expressions
46 - Solution - Write select expressions

7. Filtering Data

47 - Using the Where method
48 - Use logical operators with the Where method
49 - Exploring the OfType class definitions
50 - Use the OfType method
51 - Challenge - Filter results with Where
52 - Solution - Filter results with Where

8. Summarize and Analyze Data with Aggregates

53 - How aggregate operations work
54 - Basic aggregate operators - Sum, Average, Min, Max, Count
55 - Using lambdas in aggregate operations
56 - Specify which property to aggregate
57 - Create custom aggregate operations
58 - Reverse a sequence with a custom aggregate

9. Categorize Data with GroupBy

59 - Grouping data with the GroupBy method
60 - Creating groups with a query expression
61 - Transforming groups with an element selector
62 - Transforming groups with query expressions
63 - Renaming keys and values with a result selector
64 - Renaming keys values with query expressions
65 - Iterating over groups in LINQ
66 - Using multiple keys for grouping
67 - Flattening sequences with SelectMany
68 - Challenge - Group results by color values
69 - Solution - Group results by color values

10. Element Operations

70 - Using the First and Last methods
71 - How the FirstOrDefault method works
72 - Retrieving elements with ElementAt
73 - Using Single and SingleOrDefault

11. Perform Set Operations

74 - The Distinct method explained
75 - Understanding Cartesian product
76 - How the Intersect method works
77 - Using the Union method
78 - Filtering with the Except method
79 - Finding duplicate values in a sequence

12. Quantifying Data

80 - Explore the quantify operators
81 - Use the Any method to detect empty sequence
82 - Use the Any method to check if an element exists
83 - How the Contains method works
84 - Use the All method to check if all elements match

13. Partitioning Data

85 - Explore the Partition operators
86 - Using the Skip and Take operators
87 - Using Skip and Take with conditions

14. Extending LINQ

88 - Use LINQ in a .NET application
89 - Enhance queries with MoreLinq
90 - MoreLinq in action - Additional examples

15. Querying Databases

91 - Understand LINQ for databases
92 - A quick look at querying database data
93 - Change the database connection strings
94 - IQueryable and other DB types
95 - Install SQLite and EF core power tools
96 - Overview of the course databases
97 - Quick look at creating EF models
98 - How to use the custom DbContext
99 - Review the entity framework models

16. Databases and LINQPad

100 - Connect to included sample database
101 - Connect to another database
102 - Connect to an EF model in a .NET assembly
103 - View the database structures in LINQPad

17. Exploring Queryable Types

104 - Explore the relevant LINQ types
105 - Understand how DbContext works
106 - DbSet - The foundation of EF collections
107 - Using navigation properties in EF
108 - Add, update, and remove data in EF
109 - View the generated SQL in LINQPad

18. Interesting Queries

110 - Projection - Retrieve fewer columns
111 - Paging data with take and skip
112 - Use Find for faster key-based search
113 - Use EF navigation properties over joins
114 - Using the Contains method in queries
115 - Group query results with GroupBy
116 - Flatten child collections with SelectMany
117 - Filter records by date range

19. LINQ to DataSet

118 - ADO.NET and LINQ to DataSet
119 - Reference another query file
120 - Create and populate a DataSet
121 - Query a DataSet using AsEnumerable
122 - Access DataRow fields in a query

20. Understanding LINQ to XML

123 - Understand LINQ for XML
124 - Overview of .NET XML types

21. Loading XML Data

125 - XML data files used in this course
126 - Load XML data from a file
127 - Introduction to the XDocument class
128 - How XML namespaces affect queries
129 - Parse XML from a string
130 - Save an XML document
131 - Quick look at a LINQ to XML query

22. Working with Elements and Attributes

132 - The structure and data in the XML file
133 - Retrieve an element from XML
134 - Retrieve an attribute from XML
135 - Get elements with a namespace
136 - Get attributes with a namespace
137 - Retrieve a collection of elements
138 - Retrieve child elements from XML
139 - Use Descendants() to find child elements
140 - Retrieve attributes from XML
141 - Read values from elements and attributes

23. Editing XML Values

142 - Change element and attribute values
143 - Issues with modifying element values
144 - Use SetElementValue to add, remove, and modify child elements

24. XML Query Operators

145 - Use Query syntax to work with elements
146 - Query element values in XML
147 - Query attributes in XML
148 - Project data into an anonymous type
149 - Filter by attribute value with Where
150 - Use Where to compare values
151 - Perform aggregate queries in XML
152 - Sort query results with OrderBy
153 - Find empty elements and blank values
154 - Group XML data with GroupBy
155 - Challenge - Create a custom string output
156 - Solution - Create a custom string output
157 - Challenge - Filter elements with no content
158 - Solution - Filter elements with no content
159 - Challenge - Filter results for invalid values
160 - Solution - Filter results for invalid values

25. Introduction to LINQ to JSON

161 - Basic JSON query techniques
162 - Load data from a JSON file
163 - Query JSON with type projection
164 - Group JSON data with GroupBy

26. Continuing Your Journey

165 - More examples from the course
166 - Next steps in your LINQ journey