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 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.