Explain IEnumerable vs IQuerable in C#.
Explain IEnumerable vs IQuerable in C#.
Ask by Sandra Emily
Updated 07 Jan 2025
In C#, there are two interfaces, IEnumerable and IQueryable that are used to for data querying but they vary in where and in what mode, the query is executed. Here's a straightforward comparison:
1. IEnumerable
Namespace:
System.CollectionsPurpose: For in-memory collection iteration (e.g.,
List,Array).Execution: Queries are executed in-memory after retrieving data from the data source (e.g., database).
Usage: Suitable for querying in-memory data structures like collections.
Performance: Fetches all data into memory before applying filters.
Extension Methods: Works with LINQ-to-Objects.
Example:
2. IQueryable
Namespace:
System.LinqPurpose: For querying data sources like databases using LINQ.
Execution: Queries are translated into SQL (or equivalent) and executed on the data source (deferred execution).
Usage: Suitable for querying large datasets, especially databases (e.g., Entity Framework).
Performance: Efficient because only the required data is fetched from the source.
Extension Methods: Works with LINQ-to-SQL, LINQ-to-Entities, etc.
Example:
Hope it helps!!