Advanced LINQ Techniques in C#

LINQ (Language Integrated Query) is a powerful feature of C# that provides a way to perform queries over collections, databases, and other data sources. This section will delve into some advanced LINQ techniques in C#.

Key Concepts

Deferred Execution: LINQ queries are executed at the point of evaluation, allowing for efficient query execution.
Method Syntax vs. Query Syntax: Two ways to write LINQ queries: method syntax (more imperative) and query syntax (more declarative).

Advanced Techniques

GroupBy with Key Selector: Grouping elements in a collection based on a specified key.
```
var groupedByCategory = books.GroupBy(b => b.Category);
```

Custom Operators: Creating custom LINQ operators to extend the functionality.

public static IEnumerable<TResult> MyCustomOperator<TSource, TResult>(this IEnumerable<TSource> source, Func<TSource, TResult> selector)
{
    foreach (var item in source)
    {
        yield return selector(item);
    }
}

** deferred Execution Example

var query = from book in books
            where book.Year > 2010
            select book.Title;
// The query is not executed here. Execution will happen when the query is enumerated.
foreach (var title in query)
{
    Console.WriteLine(title);
}

LINQ to XML: Querying XML data using LINQ.

XDocument doc = XDocument.Load("books.xml");
var query = from book in doc.Descendants("book")
            where (string)book.Element("price") > "50"
            select book;

LINQ to SQL: Querying SQL databases using LINQ.

using (var db = new LibraryContext())
{
    var query = from book in db.Books
                where book.Year > 2010
                select book;
}

Advanced LINQ Techniques in C#

Key Concepts

Advanced Techniques

Further Reading