Standard Query Operators:

Standard Query Operators in LINQ are actually extension methods for the IEnumerable<T> and IQueryable<T> types. They are defined in the System.Linq.Enumerable and System.Linq.Queryable classes. There are over 50 standard query operators available in LINQ that provide different functionalities like filtering, sorting, grouping, aggregation, concatenation, etc.

Standard Query Operators in Query Syntax:

Standard Query Operators in Query Syntax

Standard Query Operators in Method Syntax:

Standard Query Operators in Method Syntax

Standard query operators in query syntax is converted into extension methods at compile time. So both are same.

Standard Query Operators can be classified based on the functionality they provide. The following table lists all the classification of Standard Query Operators:

Classification Standard Query Operators
Filtering Where, OfType
Sorting OrderBy, OrderByDescending, ThenBy, ThenByDescending, Reverse
Grouping GroupBy, ToLookup
Join GroupJoin, Join
Projection Select, SelectMany
Aggregation Aggregate, Average, Count, LongCount, Max, Min, Sum
Quantifiers All, Any, Contains
Elements ElementAt, ElementAtOrDefault, First, FirstOrDefault, Last, LastOrDefault, Single, SingleOrDefault
Set Distinct, Except, Intersect, Union
Partitioning Skip, SkipWhile, Take, TakeWhile
Concatenation Concat
Equality SequenceEqual
Generation DefaultEmpty, Empty, Range, Repeat
Conversion AsEnumerable, AsQueryable, Cast, ToArray, ToDictionary, ToList

Learn each Standard Query Operators in the next sections.