C#: What is LINQ in C#?

LINQ (Language Integrated Query) — standard query operators for data manipulation.

Two syntaxes:

1. Query syntax (SQL-like):

1var result = from s in students
2             where s.Age > 18
3             orderby s.Name
4             select s.Name;

2. Method syntax (fluent):

1var result = students
2    .Where(s => s.Age > 18)
3    .OrderBy(s => s.Name)
4    .Select(s => s.Name);

Both produce identical IL code. Method syntax is more common in practice.

Key operators:

• Filtering: Where, OfType
• Projection: Select, SelectMany
• Ordering: OrderBy, ThenBy, Reverse
• Grouping: GroupBy, ToLookup
• Aggregation: Count, Sum, Average, Min, Max