Explain the differences between the IQueryable and IEnumerable interfaces in the context of data operations.

IEnumerable and IQueryable are interfaces in C# used for working with collections and queries, but they have different purposes and behaviors:

• IEnumerable<T> — represents a collection that can be iterated over. Data queries are executed in-memory. Suitable for working with local collections, such as lists or arrays.

• IQueryable<T> — extends IEnumerable<T> and allows building queries that can be translated into expressions, such as SQL queries. Queries are executed on the data source side (e.g., a database), which allows for query optimization and reducing the amount of data transferred.

Key differences:

Feature	IEnumerable<T>	IQueryable<T>
Execution location	In memory (client-side)	On the server (data source)
Data type	Any collections	Data sources supporting LINQ (e.g., Entity Framework)
Support for deferred execution	Yes	Yes
Usage	Iterating over elements	Building and executing queries

Example:

IEnumerable<Product> products = GetProducts(); // local collection
var cheapProducts = products.Where(p => p.Price < 100); // filtering in memory

IQueryable<Product> queryableProducts = dbContext.Products; // query to DB
var cheapProductsFromDb = queryableProducts.Where(p => p.Price < 100); // SQL query to DB