LINQ Syntax Forms

Vaibhav • September 11, 2025

In the previous article, we introduced LINQ as a powerful feature that allows querying data directly within C# code. Now, we’ll explore the two primary syntax forms LINQ offers: query syntax and method syntax. Understanding both styles is essential because they each have strengths depending on the complexity and readability of your query.

Query Syntax - SQL-like and Declarative

Query syntax is often described as “SQL-like” because it resembles the structure of SQL queries. It’s declarative, meaning you describe what you want rather than how to get it. This style is especially useful for beginners and for complex queries involving joins and groupings.

List numbers = new List { 1, 2, 3, 4, 5, 6 };

var evens = from n in numbers
            where n % 2 == 0
            select n;

This query reads like a sentence: “from n in numbers, where n is even, select n.” It’s easy to follow and clearly expresses intent. The from clause introduces the data source, where filters it, and select projects the result.

Method Syntax - Fluent and Functional

Method syntax uses extension methods and lambda expressions. It’s more compact and fluent, chaining operations together. This style is preferred for simple queries and when you’re comfortable with lambda expressions.

var evens = numbers.Where(n => n % 2 == 0);

Here, Where is an extension method on List<int>. The lambda n => n % 2 == 0 defines the filtering condition. This syntax is concise and expressive, especially when chaining multiple operations.

Comparing Query and Method Syntax

Both syntaxes produce the same result and are interchangeable. However, each has scenarios where it shines. Query syntax is better for readability in complex queries, while method syntax is more flexible and integrates naturally with other C# features.

// Query syntax
var result = from fruit in fruits
             where fruit.StartsWith("a")
             orderby fruit
             select fruit;

// Method syntax
var result = fruits
    .Where(f => f.StartsWith("a"))
    .OrderBy(f => f);

Both queries filter fruits starting with “a” and sort them alphabetically. The method syntax uses chained calls, while the query syntax uses keywords. The choice often comes down to personal preference and the complexity of the query.

Using Anonymous Types in Query Syntax

LINQ allows projecting data into anonymous types, which is especially useful when you want to shape the result without creating a new class.

var projections = from fruit in fruits
                  select new { Name = fruit, Length = fruit.Length };

Each item in projections is an anonymous object with Name and Length properties. This is useful for displaying or transforming data without modifying the original structure.

Chaining in Method Syntax

Method syntax supports fluent chaining, allowing you to build complex queries step-by-step. This is ideal for scenarios where you want to apply multiple transformations.

var result = fruits
    .Where(f => f.Contains("a"))
    .OrderBy(f => f)
    .Select(f => f.ToUpper());

This query filters fruits containing “a”, sorts them, and converts each to uppercase. Each method returns a new sequence, allowing further chaining.

Mixing Syntax Forms - What to Avoid

While it’s technically possible to mix query and method syntax, it’s discouraged. Mixing styles can reduce readability and confuse intent. Stick to one style per query for clarity.

Query Syntax Limitations

Query syntax doesn’t support all LINQ operations. For example, Count, Any, and First are only available in method syntax. In such cases, you’ll need to switch to method syntax.

int count = fruits.Count(f => f.StartsWith("a"));
bool hasApple = fruits.Any(f => f == "apple");

These queries count fruits starting with “a” and check if “apple” exists. Query syntax doesn’t support these directly, so method syntax is required.

Using Let in Query Syntax

The let keyword allows you to introduce intermediate variables in query syntax. This improves readability and avoids repeating expressions.

var result = from fruit in fruits
             let upper = fruit.ToUpper()
             where upper.StartsWith("A")
             select upper;

Here, let creates a variable upper that stores the uppercase version of each fruit. This is then used in the where and select clauses.

Using Multiple From Clauses

Query syntax supports multiple from clauses, which is useful for flattening nested collections. This is similar to a cross join in SQL.

List fruits = new List { "apple", "banana" };
List vowels = new List { 'a', 'e', 'i', 'o', 'u' };

var matches = from fruit in fruits
              from vowel in vowels
              where fruit.Contains(vowel)
              select new { fruit, vowel };

This query finds all vowel matches in each fruit. The result is a sequence of anonymous objects showing which vowels appear in which fruits.

Using Into for Continuation

The into keyword allows you to continue a query after a select or group. This is useful for chaining additional operations.

var result = from fruit in fruits
             where fruit.Length > 5
             select fruit.ToUpper() into longFruits
             where longFruits.Contains("A")
             select longFruits;

Here, into creates a new identifier longFruits that holds the result of the first select. The query then continues with additional filtering.

Performance Considerations

Both syntax forms compile to the same underlying code and have similar performance characteristics. However, method syntax may offer more control and flexibility, especially when using custom extension methods or chaining advanced operations.

Choosing the Right Syntax

There’s no one-size-fits-all answer. Use query syntax when readability is paramount, especially for beginners or when working with complex joins and groupings. Use method syntax when you need concise, fluent chaining or access to advanced methods.

Summary

LINQ offers two syntax forms - query and method - each with its own strengths. Query syntax is declarative and readable, ideal for complex queries. Method syntax is fluent and flexible, perfect for chaining and advanced operations. Understanding both styles allows you to write expressive, maintainable LINQ queries that suit your data and your team’s coding style.

In the next article, we’ll dive into Where Clauses - the backbone of filtering in LINQ, and how to use them effectively to extract meaningful subsets of data.