What is the use of IQueryable in the context of Linq.

Sandeep Shekhawat

15y4.4kLINQ

means How can use IQueryable and how it is better from IEnumerable?

3 Replies

Know the answer? Post it — somebody with the same question will find it here.

Sandeep Shekhawat15y ago
Sorry Jagan sir i could not understand this. Please explain in general language as teaching sir not writing sir please.
0
15y ago
The primary difference is that the extension methods defined for IQueryable take Expression objects instead of Functional objects, meaning the delegate it receives is an expression tree instead of a method to invoke.
IEnumerable is great for working with in-memory collections, but IQueryable allows for a remote data source, like a database or web service.
IEnumerable doesn't have the concept of moving between items, it is a forward only collection. It's very minimalistic; something that most any data source can provide. Using only this minimal functionality, LINQ can provide all of these great operators.
IQueryable is a very powerful feature that enables a variety of interesting deferred execution scenarios (like paging and composition based queries).
Hope this helps !!!
Source

http://jonkruger.com/blog/2007/10/19/iqueryable-vs-ienumerable-in-linq-to-sql-queries/
0
Jaganathan Bantheswaran15y ago
Hi,

First of all, IQueryable extends the IEnumerable interface, so anything you can do with a "plain" IEnumerable, you can also do with an IQueryable.

IEnumerable just has a GetEnumerator() method that returns an Enumerator for which you can call its MoveNext() method to iterate through a sequence of T.

What IQueryable has that IEnumerable doesn't are two properties in particular—one that points to a query provider (e.g., a LINQ to SQL provider) and another one pointing to a query expression representing the IQueryable object as a runtime-traversable expression that can be understood by the given query provider (for the most part, you can't give a LINQ to SQL expression to a LINQ to Entities provider without an exception being thrown).

The expression can simply be a constant expression of the object itself or a more complex tree of a composed set of query operators and operands. The query provider's IQueryProvider.Execute() or IQueryProvider.CreateQuery() methods are called with an Expression passed to it, and then either a query result or another IQueryable is returned, respectively.

Source: Link
0