项目
11/18/2011

Queryable.Min<TSource, TResult> Method (IQueryable<TSource>, Expression<Func<TSource, TResult>>)

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Invokes a projection function on each element of a generic IQueryable<T> and returns the minimum resulting value.

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

Syntax

'Declaration
<ExtensionAttribute> _
Public Shared Function Min(Of TSource, TResult) ( _
    source As IQueryable(Of TSource), _
    selector As Expression(Of Func(Of TSource, TResult)) _
) As TResult

public static TResult Min<TSource, TResult>(
    this IQueryable<TSource> source,
    Expression<Func<TSource, TResult>> selector
)

Type Parameters

TSource
The type of the elements of source.

TResult
The type of the value returned by the function represented by selector.

Parameters

source
Type: System.Linq.IQueryable<TSource>
A sequence of values to determine the minimum of.

selector
Type: System.Linq.Expressions.Expression<Func<TSource, TResult>>
A projection function to apply to each element.

Return Value

Type: TResult
The minimum value in the sequence.

Usage Note

In Visual Basic and C#, you can call this method as an instance method on any object of type IQueryable<TSource>. When you use instance method syntax to call this method, omit the first parameter.

Exceptions

Exception	Condition
ArgumentNullException	source or selector is nulla null reference (Nothing in Visual Basic).

Remarks

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 Min<TSource, TResult>(IQueryable<TSource>, Expression<Func<TSource, TResult>>) method generates a MethodCallExpression that represents calling Min<TSource, TResult>(IQueryable<TSource>, Expression<Func<TSource, TResult>>) 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 Min<TSource, TResult>(IQueryable<TSource>, Expression<Func<TSource, TResult>>) depends on the implementation of the type of the source parameter. The expected behavior is that it invokes selector on each element in source and returns the minimum value.

Examples

The following code example demonstrates how to use Min<TSource, TResult>(IQueryable<TSource>, Expression<Func<TSource, TResult>>) to determine the minimum value in a sequence of projected values.

   Structure Pet
      Public Name As String
      Public Age As Integer
   End Structure

   Shared Sub MinEx2()
      Dim pets() As Pet = {New Pet With {.Name = "Barley", .Age = 8}, _
                     New Pet With {.Name = "Boots", .Age = 4}, _
                     New Pet With {.Name = "Whiskers", .Age = 1}}

      ' Get the Pet object that has the smallest Age value.
      Dim min As Integer = pets.AsQueryable().Min(Function(pet) pet.Age)

      outputBlock.Text &= String.Format("The youngest animal is age {0}.", min) & vbCrLf
   End Sub

   'This code produces the following output:

   'The youngest animal is age 1.

         class Pet
         {
            public string Name { get; set; }
            public int Age { get; set; }
         }

         public static void MinEx2()
         {
            Pet[] pets = { new Pet { Name="Barley", Age=8 },
                               new Pet { Name="Boots", Age=4 },
                               new Pet { Name="Whiskers", Age=1 } };

            // Get the Pet object that has the smallest Age value.
            int min = pets.AsQueryable().Min(pet => pet.Age);

            outputBlock.Text += String.Format("The youngest animal is age {0}.", min) + "\n";
         }

         /*
             This code produces the following output:

             The youngest animal is age 1.  
         */

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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