Voorbeelden van op methoden gebaseerde querysyntaxis: statistische operators

Artikel
03/05/2024

De voorbeelden in dit onderwerp laten zien hoe u de Aggregatemethoden , , Average, LongCount Counten Min Max Sum methoden gebruikt om query's uit te voeren op het AdventureWorks Sales Model met behulp van op methoden gebaseerde querysyntaxis. Het AdventureWorks Sales Model dat in deze voorbeelden wordt gebruikt, is gebaseerd op de tabellen Contact, Adres, Product, SalesOrderHeader en SalesOrderDetail in de voorbeelddatabase AdventureWorks.

In de voorbeelden in dit onderwerp worden de volgende using/Imports instructies gebruikt:

using System;
using System.Data;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Objects;
using System.Globalization;
using System.Data.EntityClient;
using System.Data.SqlClient;
using System.Data.Common;


Option Explicit On
Option Strict On
Imports System.Data.Objects
Imports System.Globalization

Gemiddeld

Opmerking

In het volgende voorbeeld wordt de methode gebruikt om de Average gemiddelde catalogusprijs van de producten te vinden.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<Product> products = context.Products;

    Decimal averageListPrice =
        products.Average(product => product.ListPrice);

    Console.WriteLine("The average list price of all the products is ${0}",
        averageListPrice);
}

Using context As New AdventureWorksEntities
    Dim products As ObjectSet(Of Product) = context.Products

    Dim averageListPrice As Decimal = _
        products.Average(Function(prod) prod.ListPrice)

    Console.WriteLine("The average list price of all the products is ${0}", _
            averageListPrice)
End Using

Opmerking

In het volgende voorbeeld wordt de methode gebruikt om de Average gemiddelde catalogusprijs van de producten van elke stijl te vinden.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<Product> products = context.Products;

    var query = from product in products
                group product by product.Style into g
                select new
                {
                    Style = g.Key,
                    AverageListPrice =
                        g.Average(product => product.ListPrice)
                };

    foreach (var product in query)
    {
        Console.WriteLine("Product style: {0} Average list price: {1}",
            product.Style, product.AverageListPrice);
    }
}

Using context As New AdventureWorksEntities
    Dim products As ObjectSet(Of Product) = context.Products

    Dim query = _
        From prod In products _
        Let styl = prod.Style _
        Group prod By styl Into g = Group _
        Select New With _
        { _
            .Style = styl, _
            .AverageListPrice = g.Average(Function(p) p.ListPrice) _
        }

    For Each prod In query
        Console.WriteLine("Product style: {0} Average list price: {1}", _
            prod.Style, prod.AverageListPrice)
    Next
End Using

Opmerking

In het volgende voorbeeld wordt de Average methode gebruikt om het gemiddelde verschuldigde totaal te vinden.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    Decimal averageTotalDue = orders.Average(order => order.TotalDue);
    Console.WriteLine("The average TotalDue is {0}.", averageTotalDue);
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim averageTotalDue As Decimal = _
        orders.Average(Function(ord) ord.TotalDue)

    Console.WriteLine("The average TotalDue is {0}.", averageTotalDue)
End Using

Opmerking

In het volgende voorbeeld wordt de Average methode gebruikt om het gemiddelde verschuldigde totaal voor elke contactpersoon-id op te halen.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    var query =
        from order in orders
        group order by order.Contact.ContactID into g
        select new
        {
            Category = g.Key,
            averageTotalDue = g.Average(order => order.TotalDue)
        };

    foreach (var order in query)
    {
        Console.WriteLine("ContactID = {0} \t Average TotalDue = {1}",
            order.Category, order.averageTotalDue);
    }
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim query = _
        From ord In orders _
        Let contID = ord.Contact.ContactID _
        Group ord By contID Into g = Group _
        Select New With _
        { _
            .Category = contID, _
            .averageTotalDue = _
                g.Average(Function(ord) ord.TotalDue) _
         }

    For Each ord In query
        Console.WriteLine("ContactID = {0} " & vbTab & _
            " Average TotalDue = {1}", _
            ord.Category, ord.averageTotalDue)
    Next
End Using

Opmerking

In het volgende voorbeeld wordt de Average methode gebruikt om de orders op te halen met het gemiddelde verschuldigde totaal voor elke contactpersoon.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    var query =
        from order in orders
        group order by order.Contact.ContactID into g
        let averageTotalDue = g.Average(order => order.TotalDue)
        select new
        {
            Category = g.Key,
            CheapestProducts =
                g.Where(order => order.TotalDue == averageTotalDue)
        };

    foreach (var orderGroup in query)
    {
        Console.WriteLine("ContactID: {0}", orderGroup.Category);
        foreach (var order in orderGroup.CheapestProducts)
        {
            Console.WriteLine("Average total due for SalesOrderID {1} is: {0}",
                order.TotalDue, order.SalesOrderID);
        }
        Console.Write("\n");
    }
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim query = _
        From ord In orders _
        Let contID = ord.Contact.ContactID _
        Group ord By contID Into g = Group _
        Let averageTotalDue = g.Average(Function(ord) ord.TotalDue) _
        Select New With _
        { _
            .Category = contID, _
            .CheapestProducts = _
                g.Where(Function(ord) ord.TotalDue = averageTotalDue) _
         }

    For Each orderGroup In query
        Console.WriteLine("ContactID: {0}", orderGroup.Category)
        For Each ord In orderGroup.CheapestProducts
            Console.WriteLine("Average total due for SalesOrderID {1} is: {0}", _
                ord.TotalDue, ord.SalesOrderID)
        Next
        Console.Write(vbNewLine)
    Next
End Using

Tellen

Opmerking

In het volgende voorbeeld wordt de Count methode gebruikt om het aantal producten in de tabel Product te retourneren.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<Product> products = context.Products;

    int numProducts = products.Count();

    Console.WriteLine("There are {0} products.", numProducts);
}

Using context As New AdventureWorksEntities
    Dim products As ObjectSet(Of Product) = context.Products

    Dim numProducts As Integer = products.Count()

    Console.WriteLine("There are {0} products.", numProducts)
End Using

Opmerking

In het volgende voorbeeld wordt de Count methode gebruikt om een lijst met contact-id's te retourneren en hoeveel orders elk heeft.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<Contact> contacts = context.Contacts;

    //Can't find field SalesOrderContact
    var query =
        from contact in contacts
        select new
        {
            CustomerID = contact.ContactID,
            OrderCount = contact.SalesOrderHeaders.Count()
        };

    foreach (var contact in query)
    {
        Console.WriteLine("CustomerID = {0} \t OrderCount = {1}",
            contact.CustomerID,
            contact.OrderCount);
    }
}

Using context As New AdventureWorksEntities
    Dim contacts As ObjectSet(Of Contact) = context.Contacts

    Dim query = _
        From cont In contacts _
        Select New With _
        { _
            .CustomerID = cont.ContactID, _
            .OrderCount = cont.SalesOrderHeaders.Count() _
         }

    For Each cont In query
        Console.WriteLine("CustomerID = {0}   OrderCount = {1}", _
               cont.CustomerID, cont.OrderCount)
    Next
End Using

Opmerking

In het volgende voorbeeld worden producten gegroepeerd op kleur en wordt de Count methode gebruikt om het aantal producten in elke kleurgroep te retourneren.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<Product> products = context.Products;

    var query =
        from product in products
        group product by product.Color into g
        select new { Color = g.Key, ProductCount = g.Count() };

    foreach (var product in query)
    {
        Console.WriteLine("Color = {0} \t ProductCount = {1}",
            product.Color,
            product.ProductCount);
    }
}

Using context As New AdventureWorksEntities
    Dim products As ObjectSet(Of Product) = context.Products

    Dim query = _
        From prod In products _
        Let pc = prod.Color _
        Group prod By pc Into g = Group _
        Select New With {.Color = pc, .ProductCount = g.Count()}

    For Each prod In query
        Console.WriteLine("Color = {0} " & vbTab & " ProductCount = {1}", _
            prod.Color, prod.ProductCount)
    Next
End Using

LongCount

Opmerking

In het volgende voorbeeld wordt het aantal contactpersonen als een lang geheel getal geteld.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<Contact> contacts = context.Contacts;

    long numberOfContacts = contacts.LongCount();
    Console.WriteLine("There are {0} Contacts", numberOfContacts);
}

Using context As New AdventureWorksEntities
    Dim contacts As ObjectSet(Of Contact) = context.Contacts

    Dim numberOfContacts As Long = contacts.LongCount()

    Console.WriteLine("There are {0} Contacts", numberOfContacts)
End Using

Max

Opmerking

In het volgende voorbeeld wordt de Max methode gebruikt om het grootste verschuldigde totaal op te halen.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    Decimal maxTotalDue = orders.Max(w => w.TotalDue);
    Console.WriteLine("The maximum TotalDue is {0}.",
        maxTotalDue);
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim maxTotalDue As Decimal = _
        orders.Max(Function(ord) ord.TotalDue)

    Console.WriteLine("The maximum TotalDue is {0}.", maxTotalDue)
End Using

Opmerking

In het volgende voorbeeld wordt de Max methode gebruikt om het grootste totaal op te halen voor elke contactpersoon-id.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    var query =
        from order in orders
        group order by order.Contact.ContactID into g
        select new
        {
            Category = g.Key,
            maxTotalDue =
                g.Max(order => order.TotalDue)
        };

    foreach (var order in query)
    {
        Console.WriteLine("ContactID = {0} \t Maximum TotalDue = {1}",
            order.Category, order.maxTotalDue);
    }
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim query = _
        From ord In orders _
        Let contID = ord.Contact.ContactID _
        Group ord By contID Into g = Group _
        Select New With _
        { _
            .Category = contID, _
            .MaxTotalDue = _
                g.Max(Function(ord) ord.TotalDue) _
         }

    For Each ord In query
        Console.WriteLine("ContactID = {0} " & vbTab & _
            " Maximum TotalDue = {1}", _
            ord.Category, ord.MaxTotalDue)
    Next
End Using

Opmerking

In het volgende voorbeeld wordt de Max methode gebruikt om de orders op te halen met het grootste verschuldigde totaal voor elke contactpersoon-id.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    var query =
        from order in orders
        group order by order.Contact.ContactID into g
        let maxTotalDue = g.Max(order => order.TotalDue)
        select new
        {
            Category = g.Key,
            CheapestProducts =
                g.Where(order => order.TotalDue == maxTotalDue)
        };

    foreach (var orderGroup in query)
    {
        Console.WriteLine("ContactID: {0}", orderGroup.Category);
        foreach (var order in orderGroup.CheapestProducts)
        {
            Console.WriteLine("MaxTotalDue {0} for SalesOrderID {1}: ",
                order.TotalDue,
                order.SalesOrderID);
        }
        Console.Write("\n");
    }
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim query = _
        From ord In orders _
        Let contID = ord.Contact.ContactID _
        Group ord By contID Into g = Group _
        Let maxTotalDue = g.Max(Function(ord) ord.TotalDue) _
        Select New With _
        { _
            .Category = contID, _
            .CheapestProducts = _
                g.Where(Function(ord) ord.TotalDue = maxTotalDue) _
         }

    For Each orderGroup In query
        Console.WriteLine("ContactID: {0}", orderGroup.Category)
        For Each ord In orderGroup.CheapestProducts
            Console.WriteLine("MaxTotalDue {0} for SalesOrderID {1}: ", _
                ord.TotalDue, ord.SalesOrderID)
        Next
        Console.Write(vbNewLine)
    Next
End Using

Min

Opmerking

In het volgende voorbeeld wordt de Min methode gebruikt om het kleinste verschuldigde totaal op te halen.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    Decimal smallestTotalDue = orders.Min(totalDue => totalDue.TotalDue);
    Console.WriteLine("The smallest TotalDue is {0}.",
        smallestTotalDue);
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim smallestTotalDue As Decimal = _
        orders.Min(Function(totDue) totDue.TotalDue)

    Console.WriteLine("The smallest TotalDue is {0}.", _
        smallestTotalDue)
End Using

Opmerking

In het volgende voorbeeld wordt de Min methode gebruikt om het kleinste totaal op te halen dat voor elke contactpersoon-id moet worden betaald.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    var query =
        from order in orders
        group order by order.Contact.ContactID into g
        select new
        {
            Category = g.Key,
            smallestTotalDue =
                g.Min(order => order.TotalDue)
        };

    foreach (var order in query)
    {
        Console.WriteLine("ContactID = {0} \t Minimum TotalDue = {1}",
            order.Category, order.smallestTotalDue);
    }
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim query = _
        From ord In orders _
        Let contID = ord.Contact.ContactID _
        Group ord By contID Into g = Group _
        Select New With _
        { _
            .Category = contID, _
            .smallestTotalDue = _
                g.Min(Function(o) o.TotalDue) _
         }

    For Each ord In query
        Console.WriteLine("ContactID = {0} " & vbTab & _
            " Minimum TotalDue = {1}", ord.Category, ord.smallestTotalDue)
    Next
End Using

Opmerking

In het volgende voorbeeld wordt de Min methode gebruikt om de orders op te halen met het kleinste totale verschuldigde bedrag voor elke contactpersoon.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    var query =
        from order in orders
        group order by order.Contact.ContactID into g
        let minTotalDue = g.Min(order => order.TotalDue)
        select new
        {
            Category = g.Key,
            smallestTotalDue =
                g.Where(order => order.TotalDue == minTotalDue)
        };

    foreach (var orderGroup in query)
    {
        Console.WriteLine("ContactID: {0}", orderGroup.Category);
        foreach (var order in orderGroup.smallestTotalDue)
        {
            Console.WriteLine("Minimum TotalDue {0} for SalesOrderID {1}: ",
                order.TotalDue,
                order.SalesOrderID);
        }
        Console.Write("\n");
    }
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim query = _
        From ord In orders _
        Let contID = ord.Contact.ContactID _
        Group ord By contID Into g = Group _
        Let minTotalDue = g.Min(Function(o) o.TotalDue) _
        Select New With _
        { _
            .Category = contID, _
            .smallestTotalDue = _
                g.Where(Function(o) o.TotalDue = minTotalDue) _
         }

    For Each orderGroup In query
        Console.WriteLine("ContactID: {0}", orderGroup.Category)
        For Each ord In orderGroup.smallestTotalDue
            Console.WriteLine("Minimum TotalDue {0} for SalesOrderID {1}: ", _
                ord.TotalDue, ord.SalesOrderID)
        Next
        Console.Write(vbNewLine)
    Next
End Using

Sum

Opmerking

In het volgende voorbeeld wordt de Sum methode gebruikt om het totale aantal orderhoeveelheden in de tabel SalesOrderDetail op te halen.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderDetail> orders = context.SalesOrderDetails;

    double totalOrderQty = orders.Sum(o => o.OrderQty);
    Console.WriteLine("There are a total of {0} OrderQty.",
        totalOrderQty);
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderDetail) = context.SalesOrderDetails

    Dim totalOrderQty As Double = orders.Sum(Function(o) o.OrderQty)

    Console.WriteLine("There are a total of {0} OrderQty.", _
        totalOrderQty)
End Using

Opmerking

In het volgende voorbeeld wordt de Sum methode gebruikt om het totale verschuldigde bedrag voor elke contactpersoon-id op te halen.

using (AdventureWorksEntities context = new AdventureWorksEntities())
{
    ObjectSet<SalesOrderHeader> orders = context.SalesOrderHeaders;

    var query =
        from order in orders
        group order by order.Contact.ContactID into g
        select new
        {
            Category = g.Key,
            TotalDue = g.Sum(order => order.TotalDue)
        };

    foreach (var order in query)
    {
        Console.WriteLine("ContactID = {0} \t TotalDue sum = {1}",
            order.Category, order.TotalDue);
    }
}

Using context As New AdventureWorksEntities
    Dim orders As ObjectSet(Of SalesOrderHeader) = context.SalesOrderHeaders

    Dim query = _
        From ord In orders _
        Let contID = ord.Contact.ContactID _
        Group ord By contID Into g = Group _
        Select New With _
        { _
            .Category = contID, _
            .TotalDue = g.Sum(Function(o) o.TotalDue) _
        }

    For Each ord In query
        Console.WriteLine("ContactID = {0} " & vbTab & _
            " TotalDue sum = {1}", ord.Category, ord.TotalDue)
    Next
End Using

Zie ook

Query's in LINQ naar entiteiten

Share via

Voorbeelden van op methoden gebaseerde querysyntaxis: statistische operators

Gemiddeld

Opmerking

Opmerking

Opmerking

Opmerking

Opmerking

Tellen

Opmerking

Opmerking

Opmerking

LongCount

Opmerking

Max

Opmerking

Opmerking

Opmerking

Min

Opmerking

Opmerking

Opmerking

Sum

Opmerking

Opmerking

Zie ook

Aanvullende resources