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IQueryable Interface


Provides functionality to evaluate queries against a specific data source wherein the type of the data is not specified.

Namespace:   System.Linq
Assembly:  System.Core (in System.Core.dll)

public interface IQueryable : IEnumerable


Gets the type of the element(s) that are returned when the expression tree associated with this instance of IQueryable is executed.


Gets the expression tree that is associated with the instance of IQueryable.


Gets the query provider that is associated with this data source.


Returns an enumerator that iterates through a collection.(Inherited from IEnumerable.)


Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.)


Overloaded. Converts an IEnumerable to an IQueryable.(Defined by Queryable.)


Converts the elements of an IQueryable to the specified type.(Defined by Queryable.)


Filters the elements of an IQueryable based on a specified type.(Defined by Queryable.)

The IQueryable interface is intended for implementation by query providers. It is only supposed to be implemented by providers that also implement IQueryable<T>. If the provider does not also implement IQueryable<T>, the standard query operators cannot be used on the provider's data source.

The IQueryable interface inherits the IEnumerable interface so that if it represents a query, the results of that query can be enumerated. Enumeration causes the expression tree associated with an IQueryable object to be executed. The definition of "executing an expression tree" is specific to a query provider. For example, it may involve translating the expression tree to an appropriate query language for the underlying data source. Queries that do not return enumerable results are executed when the Execute method is called.

For more information about how to create your own LINQ provider, see LINQ: Building an IQueryable Provider on MSDN Blogs.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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