Queryable.Aggregate<'TSource> Method (IQueryable<'TSource>, Expression<Func<'TSource, 'TSource, 'TSource>>)
Applies an accumulator function over a sequence.
Assembly: System.Core (in System.Core.dll)
static member Aggregate<'TSource> : source:IQueryable<'TSource> * func:Expression<Func<'TSource, 'TSource, 'TSource>> > 'TSource
Parameters
 source

Type:
System.Linq.IQueryable<'TSource>
A sequence to aggregate over.
 func

Type:
System.Linq.Expressions.Expression<Func<'TSource, 'TSource, 'TSource>>
An accumulator function to apply to each element.
Return Value
Type: TSourceThe final accumulator value.
Type Parameters
 TSource
The type of the elements of source.
Exception  Condition 

ArgumentNullException  source or func is null. 
InvalidOperationException  source contains no elements. 
This method has at least one parameter of type Expression<'TDelegate> whose type argument is one of the Func<'T, 'TResult> types. For these parameters, you can pass in a lambda expression and it will be compiled to an Expression<'TDelegate>.
The Aggregate<'TSource>(IQueryable<'TSource>, Expression<Func<'TSource, 'TSource, 'TSource>>) method generates a MethodCallExpression that represents calling Aggregate<'TSource>(IQueryable<'TSource>, Expression<Func<'TSource, 'TSource, 'TSource>>) itself as a constructed generic method. It then passes the MethodCallExpression to the Execute<'TResult>(Expression) method of the IQueryProvider represented by the Provider property of the source parameter.
The query behavior that occurs as a result of executing an expression tree that represents calling Aggregate<'TSource>(IQueryable<'TSource>, Expression<Func<'TSource, 'TSource, 'TSource>>) depends on the implementation of the type of the source parameter. The expected behavior is that the specified function, func, is applied to each value in the source sequence and the accumulated value is returned. The first value in source is used as the seed value for the accumulated value, which corresponds to the first parameter in func.
To simplify common aggregation operations, the set of standard query operators also includes two counting methods, Count<'TSource> and LongCount<'TSource>, and four numeric aggregation methods, namely Max<'TSource>, Min<'TSource>, Sum, and Average.
Available since 8
.NET Framework
Available since 3.5
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1