# Queryable.Sum 方法

## 重载

 Sum(IQueryable) 计算 Single 值序列的总和。Computes the sum of a sequence of Single values. Sum(IQueryable>) 计算可以为 null 的 Single 值序列的总和。Computes the sum of a sequence of nullable Single values. Sum(IQueryable>) 计算可以为 null 的 Int64 值序列的总和。Computes the sum of a sequence of nullable Int64 values. Sum(IQueryable>) 计算可以为 null 的 Int32 值序列的总和。Computes the sum of a sequence of nullable Int32 values. Sum(IQueryable>) 计算可以为 null 的 Double 值序列的总和。Computes the sum of a sequence of nullable Double values. Sum(IQueryable) 计算 Int32 值序列的总和。Computes the sum of a sequence of Int32 values. Sum(IQueryable) 计算 Int64 值序列的总和。Computes the sum of a sequence of Int64 values. Sum(IQueryable>) 计算可以为 null 的 Decimal 值序列的总和。Computes the sum of a sequence of nullable Decimal values. Sum(IQueryable) 计算 Double 值序列的总和。Computes the sum of a sequence of Double values. Sum(IQueryable) 计算 Decimal 值序列的总和。Computes the sum of a sequence of Decimal values. Sum(IQueryable, Expression>>) 计算可以为 null 的 Single 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of nullable Single values that is obtained by invoking a projection function on each element of the input sequence. Sum(IQueryable, Expression>>) 计算可以为 null 的 Int64 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of nullable Int64 values that is obtained by invoking a projection function on each element of the input sequence. Sum(IQueryable, Expression>>) 计算可以为 null 的 Int32 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of nullable Int32 values that is obtained by invoking a projection function on each element of the input sequence. Sum(IQueryable, Expression>>) 计算可以为 null 的 Double 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of nullable Double values that is obtained by invoking a projection function on each element of the input sequence. Sum(IQueryable, Expression>) 计算 Single 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of Single values that is obtained by invoking a projection function on each element of the input sequence. Sum(IQueryable, Expression>) 计算 Int64 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of Int64 values that is obtained by invoking a projection function on each element of the input sequence. Sum(IQueryable, Expression>) 计算 Int32 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of Int32 values that is obtained by invoking a projection function on each element of the input sequence. Sum(IQueryable, Expression>) 计算 Double 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of Double values that is obtained by invoking a projection function on each element of the input sequence. Sum(IQueryable, Expression>) 计算 Decimal 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of Decimal values that is obtained by invoking a projection function on each element of the input sequence. Sum(IQueryable, Expression>>) 计算可以为 null 的 Decimal 值序列之和，而该序列是通过对输入序列中的每个元素调用投影函数而获得的。Computes the sum of the sequence of nullable Decimal values that is obtained by invoking a projection function on each element of the input sequence.

## Sum(IQueryable<Single>)

``````public:
[System::Runtime::CompilerServices::Extension]
static float Sum(System::Linq::IQueryable<float> ^ source);``````
``public static float Sum (this System.Linq.IQueryable<float> source);``
``static member Sum : System.Linq.IQueryable<single> -> single``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Single)) As Single``````

#### 参数

source
IQueryable<Single>

#### 例外

`source``null``source` is `null`.

### 示例

``````List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };

float sum = numbers.AsQueryable().Sum();

Console.WriteLine("The sum of the numbers is {0}.", sum);

/*
This code produces the following output:

The sum of the numbers is 635.13.
*/

``````
``````Dim numbers As New List(Of Single)(New Single() {43.68F, 1.25F, 583.7F, 6.5F})

Dim sum As Single = numbers.AsQueryable().Sum()

MsgBox("The sum of the numbers is " & sum)

' This code produces the following output:

' The sum of the numbers is 635.13.

``````

### 注解

Sum(IQueryable<Single>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Single>) 本身。The Sum(IQueryable<Single>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Single>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum(IQueryable<Nullable<Single>>)

``````public:
[System::Runtime::CompilerServices::Extension]
static Nullable<float> Sum(System::Linq::IQueryable<Nullable<float>> ^ source);``````
``public static Nullable<float> Sum (this System.Linq.IQueryable<Nullable<float>> source);``
``static member Sum : System.Linq.IQueryable<Nullable<single>> -> Nullable<single>``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Nullable(Of Single))) As Nullable(Of Single)``````

#### 参数

source
IQueryable<Nullable<Single>>

#### 例外

`source``null``source` is `null`.

### 示例

``````float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };

float? sum = points.AsQueryable().Sum();

Console.WriteLine("Total points earned: {0}", sum);

/*
This code produces the following output:

Total points earned: 311.39
*/

``````
``````Dim points As Nullable(Of Single)() = {Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}

Dim sum As Nullable(Of Single) = points.AsQueryable().Sum()

MsgBox("Total points earned: " & sum)

'This code produces the following output:

'Total points earned: 311.39

``````

### 注解

Sum(IQueryable<Nullable<Single>>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Nullable<Single>>) 本身。The Sum(IQueryable<Nullable<Single>>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Nullable<Single>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum(IQueryable<Nullable<Int64>>)

``````public:
[System::Runtime::CompilerServices::Extension]
static Nullable<long> Sum(System::Linq::IQueryable<Nullable<long>> ^ source);``````
``public static Nullable<long> Sum (this System.Linq.IQueryable<Nullable<long>> source);``
``static member Sum : System.Linq.IQueryable<Nullable<int64>> -> Nullable<int64>``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Nullable(Of Long))) As Nullable(Of Long)``````

#### 参数

source
IQueryable<Nullable<Int64>>

#### 例外

`source``null``source` is `null`.

### 示例

``````float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };

float? sum = points.AsQueryable().Sum();

Console.WriteLine("Total points earned: {0}", sum);

/*
This code produces the following output:

Total points earned: 311.39
*/

``````
``````Dim points As Nullable(Of Single)() = {Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}

Dim sum As Nullable(Of Single) = points.AsQueryable().Sum()

MsgBox("Total points earned: " & sum)

'This code produces the following output:

'Total points earned: 311.39

``````

### 注解

Sum(IQueryable<Nullable<Int64>>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Nullable<Int64>>) 本身。The Sum(IQueryable<Nullable<Int64>>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Nullable<Int64>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum(IQueryable<Nullable<Int32>>)

``````public:
[System::Runtime::CompilerServices::Extension]
static Nullable<int> Sum(System::Linq::IQueryable<Nullable<int>> ^ source);``````
``public static Nullable<int> Sum (this System.Linq.IQueryable<Nullable<int>> source);``
``static member Sum : System.Linq.IQueryable<Nullable<int>> -> Nullable<int>``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Nullable(Of Integer))) As Nullable(Of Integer)``````

#### 参数

source
IQueryable<Nullable<Int32>>

#### 例外

`source``null``source` is `null`.

### 示例

``````float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };

float? sum = points.AsQueryable().Sum();

Console.WriteLine("Total points earned: {0}", sum);

/*
This code produces the following output:

Total points earned: 311.39
*/

``````
``````Dim points As Nullable(Of Single)() = {Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}

Dim sum As Nullable(Of Single) = points.AsQueryable().Sum()

MsgBox("Total points earned: " & sum)

'This code produces the following output:

'Total points earned: 311.39

``````

### 注解

Sum(IQueryable<Nullable<Int32>>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Nullable<Int32>>) 本身。The Sum(IQueryable<Nullable<Int32>>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Nullable<Int32>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum(IQueryable<Nullable<Double>>)

``````public:
[System::Runtime::CompilerServices::Extension]
static Nullable<double> Sum(System::Linq::IQueryable<Nullable<double>> ^ source);``````
``public static Nullable<double> Sum (this System.Linq.IQueryable<Nullable<double>> source);``
``static member Sum : System.Linq.IQueryable<Nullable<double>> -> Nullable<double>``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Nullable(Of Double))) As Nullable(Of Double)``````

#### 参数

source
IQueryable<Nullable<Double>>

#### 例外

`source``null``source` is `null`.

### 示例

``````float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };

float? sum = points.AsQueryable().Sum();

Console.WriteLine("Total points earned: {0}", sum);

/*
This code produces the following output:

Total points earned: 311.39
*/

``````
``````Dim points As Nullable(Of Single)() = {Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}

Dim sum As Nullable(Of Single) = points.AsQueryable().Sum()

MsgBox("Total points earned: " & sum)

'This code produces the following output:

'Total points earned: 311.39

``````

### 注解

Sum(IQueryable<Nullable<Double>>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Nullable<Double>>) 本身。The Sum(IQueryable<Nullable<Double>>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Nullable<Double>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum(IQueryable<Int32>)

``````public:
[System::Runtime::CompilerServices::Extension]
static int Sum(System::Linq::IQueryable<int> ^ source);``````
``public static int Sum (this System.Linq.IQueryable<int> source);``
``static member Sum : System.Linq.IQueryable<int> -> int``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Integer)) As Integer``````

#### 参数

source
IQueryable<Int32>

#### 例外

`source``null``source` is `null`.

### 示例

``````List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };

float sum = numbers.AsQueryable().Sum();

Console.WriteLine("The sum of the numbers is {0}.", sum);

/*
This code produces the following output:

The sum of the numbers is 635.13.
*/

``````
``````Dim numbers As New List(Of Single)(New Single() {43.68F, 1.25F, 583.7F, 6.5F})

Dim sum As Single = numbers.AsQueryable().Sum()

MsgBox("The sum of the numbers is " & sum)

' This code produces the following output:

' The sum of the numbers is 635.13.

``````

### 注解

Sum(IQueryable<Int32>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Int32>) 本身。The Sum(IQueryable<Int32>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Int32>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum(IQueryable<Int64>)

``````public:
[System::Runtime::CompilerServices::Extension]
static long Sum(System::Linq::IQueryable<long> ^ source);``````
``public static long Sum (this System.Linq.IQueryable<long> source);``
``static member Sum : System.Linq.IQueryable<int64> -> int64``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Long)) As Long``````

#### 参数

source
IQueryable<Int64>

#### 例外

`source``null``source` is `null`.

### 示例

``````List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };

float sum = numbers.AsQueryable().Sum();

Console.WriteLine("The sum of the numbers is {0}.", sum);

/*
This code produces the following output:

The sum of the numbers is 635.13.
*/

``````
``````Dim numbers As New List(Of Single)(New Single() {43.68F, 1.25F, 583.7F, 6.5F})

Dim sum As Single = numbers.AsQueryable().Sum()

MsgBox("The sum of the numbers is " & sum)

' This code produces the following output:

' The sum of the numbers is 635.13.

``````

### 注解

Sum(IQueryable<Int64>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Int64>) 本身。The Sum(IQueryable<Int64>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Int64>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum(IQueryable<Nullable<Decimal>>)

``````public:
[System::Runtime::CompilerServices::Extension]
static Nullable<System::Decimal> Sum(System::Linq::IQueryable<Nullable<System::Decimal>> ^ source);``````
``public static Nullable<decimal> Sum (this System.Linq.IQueryable<Nullable<decimal>> source);``
``static member Sum : System.Linq.IQueryable<Nullable<decimal>> -> Nullable<decimal>``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Nullable(Of Decimal))) As Nullable(Of Decimal)``````

#### 参数

source
IQueryable<Nullable<Decimal>>

#### 例外

`source``null``source` is `null`.

### 示例

``````float?[] points = { null, 0, 92.83F, null, 100.0F, 37.46F, 81.1F };

float? sum = points.AsQueryable().Sum();

Console.WriteLine("Total points earned: {0}", sum);

/*
This code produces the following output:

Total points earned: 311.39
*/

``````
``````Dim points As Nullable(Of Single)() = {Nothing, 0, 92.83F, Nothing, 100.0F, 37.46F, 81.1F}

Dim sum As Nullable(Of Single) = points.AsQueryable().Sum()

MsgBox("Total points earned: " & sum)

'This code produces the following output:

'Total points earned: 311.39

``````

### 注解

Sum(IQueryable<Nullable<Decimal>>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Nullable<Decimal>>) 本身。The Sum(IQueryable<Nullable<Decimal>>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Nullable<Decimal>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum(IQueryable<Double>)

``````public:
[System::Runtime::CompilerServices::Extension]
static double Sum(System::Linq::IQueryable<double> ^ source);``````
``public static double Sum (this System.Linq.IQueryable<double> source);``
``static member Sum : System.Linq.IQueryable<double> -> double``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Double)) As Double``````

#### 参数

source
IQueryable<Double>

#### 例外

`source``null``source` is `null`.

### 示例

``````List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };

float sum = numbers.AsQueryable().Sum();

Console.WriteLine("The sum of the numbers is {0}.", sum);

/*
This code produces the following output:

The sum of the numbers is 635.13.
*/

``````
``````Dim numbers As New List(Of Single)(New Single() {43.68F, 1.25F, 583.7F, 6.5F})

Dim sum As Single = numbers.AsQueryable().Sum()

MsgBox("The sum of the numbers is " & sum)

' This code produces the following output:

' The sum of the numbers is 635.13.

``````

### 注解

Sum(IQueryable<Double>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Double>) 本身。The Sum(IQueryable<Double>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Double>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum(IQueryable<Decimal>)

``````public:
[System::Runtime::CompilerServices::Extension]
static System::Decimal Sum(System::Linq::IQueryable<System::Decimal> ^ source);``````
``public static decimal Sum (this System.Linq.IQueryable<decimal> source);``
``static member Sum : System.Linq.IQueryable<decimal> -> decimal``
``````<Extension()>
Public Function Sum (source As IQueryable(Of Decimal)) As Decimal``````

#### 参数

source
IQueryable<Decimal>

#### 例外

`source``null``source` is `null`.

### 示例

``````List<float> numbers = new List<float> { 43.68F, 1.25F, 583.7F, 6.5F };

float sum = numbers.AsQueryable().Sum();

Console.WriteLine("The sum of the numbers is {0}.", sum);

/*
This code produces the following output:

The sum of the numbers is 635.13.
*/

``````
``````Dim numbers As New List(Of Single)(New Single() {43.68F, 1.25F, 583.7F, 6.5F})

Dim sum As Single = numbers.AsQueryable().Sum()

MsgBox("The sum of the numbers is " & sum)

' This code produces the following output:

' The sum of the numbers is 635.13.

``````

### 注解

Sum(IQueryable<Decimal>) 方法生成一个 MethodCallExpression，它表示作为构造的泛型方法调用 Sum(IQueryable<Decimal>) 本身。The Sum(IQueryable<Decimal>) method generates a MethodCallExpression that represents calling Sum(IQueryable<Decimal>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Single>>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<float> Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, Nullable<float>> ^> ^ selector);``````
``public static Nullable<float> Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,Nullable<float>>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, Nullable<single>>> -> Nullable<single>``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Nullable(Of Single)))) As Nullable(Of Single)``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Nullable<Single>>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Single>>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Single>>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Int64>>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<long> Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, Nullable<long>> ^> ^ selector);``````
``public static Nullable<long> Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,Nullable<long>>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, Nullable<int64>>> -> Nullable<int64>``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Nullable(Of Long)))) As Nullable(Of Long)``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Nullable<Int64>>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Int64>>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Int64>>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Int32>>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<int> Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, Nullable<int>> ^> ^ selector);``````
``public static Nullable<int> Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,Nullable<int>>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, Nullable<int>>> -> Nullable<int>``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Nullable(Of Integer)))) As Nullable(Of Integer)``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Nullable<Int32>>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Int32>>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Int32>>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Double>>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<double> Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, Nullable<double>> ^> ^ selector);``````
``public static Nullable<double> Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,Nullable<double>>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, Nullable<double>>> -> Nullable<double>``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Nullable(Of Double)))) As Nullable(Of Double)``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Nullable<Double>>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Double>>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Double>>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Single>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static float Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, float> ^> ^ selector);``````
``public static float Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,float>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, single>> -> single``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Single))) As Single``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Single>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Single>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Single>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int64>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static long Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, long> ^> ^ selector);``````
``public static long Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,long>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, int64>> -> int64``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Long))) As Long``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Int64>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int64>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int64>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static int Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, int> ^> ^ selector);``````
``public static int Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,int>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, int>> -> int``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Integer))) As Integer``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Int32>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Int32>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Double>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static double Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, double> ^> ^ selector);``````
``public static double Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,double>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, double>> -> double``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Double))) As Double``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Double>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Double>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Double>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Decimal>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static System::Decimal Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, System::Decimal> ^> ^ selector);``````
``public static decimal Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,decimal>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, decimal>> -> decimal``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Decimal))) As Decimal``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Decimal>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Decimal>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Decimal>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.

## Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Decimal>>>)

``````public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
static Nullable<System::Decimal> Sum(System::Linq::IQueryable<TSource> ^ source, System::Linq::Expressions::Expression<Func<TSource, Nullable<System::Decimal>> ^> ^ selector);``````
``public static Nullable<decimal> Sum<TSource> (this System.Linq.IQueryable<TSource> source, System.Linq.Expressions.Expression<Func<TSource,Nullable<decimal>>> selector);``
``static member Sum : System.Linq.IQueryable<'Source> * System.Linq.Expressions.Expression<Func<'Source, Nullable<decimal>>> -> Nullable<decimal>``
``````<Extension()>
Public Function Sum(Of TSource) (source As IQueryable(Of TSource), selector As Expression(Of Func(Of TSource, Nullable(Of Decimal)))) As Nullable(Of Decimal)``````

#### 类型参数

TSource

`source` 的元素类型。The type of the elements of `source`.

#### 参数

source
IQueryable<TSource>

selector
Expression<Func<TSource,Nullable<Decimal>>>

#### 例外

`source``selector``null``source` or `selector` is `null`.

### 示例

``````class Package
{
public string Company { get; set; }
public double Weight { get; set; }
}

public static void SumEx3()
{
List<Package> packages =
new List<Package>
{ new Package { Company = "Coho Vineyard", Weight = 25.2 },
new Package { Company = "Lucerne Publishing", Weight = 18.7 },
new Package { Company = "Wingtip Toys", Weight = 6.0 },
new Package { Company = "Adventure Works", Weight = 33.8 } };

// Calculate the sum of all package weights.
double totalWeight = packages.AsQueryable().Sum(pkg => pkg.Weight);

Console.WriteLine("The total weight of the packages is: {0}", totalWeight);
}

/*
This code produces the following output:

The total weight of the packages is: 83.7
*/

``````
``````Structure Package
Public Company As String
Public Weight As Double
End Structure

Shared Sub SumEx3()
Dim packages As New List(Of Package)(New Package() { _
New Package With {.Company = "Coho Vineyard", .Weight = 25.2}, _
New Package With {.Company = "Lucerne Publishing", .Weight = 18.7}, _
New Package With {.Company = "Wingtip Toys", .Weight = 6.0}, _
New Package With {.Company = "Adventure Works", .Weight = 33.8}})

' Calculate the sum of all package weights.
Dim totalWeight As Double = packages.AsQueryable().Sum(Function(pkg) pkg.Weight)

MsgBox("The total weight of the packages is: " & totalWeight)
End Sub

'This code produces the following output:

'The total weight of the packages is: 83.7

``````

### 注解

The Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Decimal>>>) method generates a MethodCallExpression that represents calling Sum<TSource>(IQueryable<TSource>, Expression<Func<TSource,Nullable<Decimal>>>) itself as a constructed generic method. 然后，它将 MethodCallExpression 传递到 IQueryProviderExecute<TResult>(Expression) 方法（由 `source` 参数的 Provider 属性表示）。It then passes the MethodCallExpression to the Execute<TResult>(Expression) method of the IQueryProvider represented by the Provider property of the `source` parameter.