C# LINQ Join Query Syntax（開発者向けの動作方法）

LINQ Join演算子の構文

LINQ Join演算子の構文は表現が豊かで、SQL結合に似たパターンに従います。 基本的な構文は次の通りです：

var queryResult = 
    from element1 in collection1
    join element2 in collection2 on element1.Key equals element2.Key
    select new { element1, element2 };

var queryResult = 
    from element1 in collection1
    join element2 in collection2 on element1.Key equals element2.Key
    select new { element1, element2 };

Dim queryResult = From element1 In collection1
	Join element2 In collection2 On element1.Key Equals element2.Key
	Select New With {
		Key element1,
		Key element2
	}

この構文において：

• element1とelement2は、collection1とcollection2の要素を表す変数です。
• element1.Keyとelement2.Keyは結合操作の基準として使用されるプロパティです。
• equalsキーワードが結合の条件を指定します。
• select句が、両方のコレクションから要素を組み合わせた新しいオブジェクトを生成します。

LINQ結合の種類

LINQは、以下を含む多様な結合をサポートしています：

1. 内部結合: 両方のコレクションでキーが一致する要素のみを返します。

   var innerJoin = from customer in customers
                   join order in orders on customer.CustomerID equals order.CustomerID // join orders to customers based on the customer ID key
                   select new { customer.CustomerID, customer.CustomerName, order.OrderID }; // create a new anonymous object based on the objects obtained from the join

   var innerJoin = from customer in customers
                   join order in orders on customer.CustomerID equals order.CustomerID // join orders to customers based on the customer ID key
                   select new { customer.CustomerID, customer.CustomerName, order.OrderID }; // create a new anonymous object based on the objects obtained from the join

   Dim innerJoin = From customer In customers ' create a new anonymous object based on the objects obtained from the join
   	Join order In orders On customer.CustomerID Equals order.CustomerID
   	Select New With {
   		Key customer.CustomerID,
   		Key customer.CustomerName,
   		Key order.OrderID
   	}

   $vbLabelText   $csharpLabel

2. 左外部結合（デフォルト）: 左のコレクションのすべての要素と右のコレクションの一致する要素を返します。 一致が見つからない場合、結果には右側の要素のデフォルト値が含まれます。

   var leftOuterJoin = from customer in customers
                       join order in orders on customer.CustomerID equals order.CustomerID into customerOrders
                       from co in customerOrders.DefaultIfEmpty()
                       select new { customer.CustomerID, customer.CustomerName, OrderID = co?.OrderID ?? -1 };

   var leftOuterJoin = from customer in customers
                       join order in orders on customer.CustomerID equals order.CustomerID into customerOrders
                       from co in customerOrders.DefaultIfEmpty()
                       select new { customer.CustomerID, customer.CustomerName, OrderID = co?.OrderID ?? -1 };

   Dim leftOuterJoin = From customer In customers
   	Group Join order In orders On customer.CustomerID Equals order.CustomerID Into customerOrders = Group
   	From co In customerOrders.DefaultIfEmpty()
   	Select New With {
   		Key customer.CustomerID,
   		Key customer.CustomerName,
   		Key .OrderID = If(co?.OrderID, -1)
   	}

   $vbLabelText   $csharpLabel

3. グループ結合: 左のコレクションの要素を右のコレクションの一致する要素とグループ化します。

   var groupJoin = from customer in customers
                   join order in orders on customer.CustomerID equals order.CustomerID into customerOrders
                   select new { customer.CustomerID, customer.CustomerName, Orders = customerOrders };

   var groupJoin = from customer in customers
                   join order in orders on customer.CustomerID equals order.CustomerID into customerOrders
                   select new { customer.CustomerID, customer.CustomerName, Orders = customerOrders };

   Dim groupJoin = From customer In customers
   	Group Join order In orders On customer.CustomerID Equals order.CustomerID Into customerOrders = Group
   	Select New With {
   		Key customer.CustomerID,
   		Key customer.CustomerName,
   		Key .Orders = customerOrders
   	}

   $vbLabelText   $csharpLabel

IronPDFのインストール：クイックスタート

C#プロジェクトでIronPDFライブラリを活用し始めるには、IronPDF NuGetパッケージを簡単にインストールすることができます。 パッケージマネージャーコンソールで以下のコマンドを使用してください：

Install-Package IronPdf 

または、NuGetパッケージマネージャーで「IronPDF」を検索し、そこからインストールすることも可能です。

シナリオ1：PDF生成前のデータ統合

異なるデータソースからのデータをPDF生成プロセスを開始する前に統合することが目標であれば、LINQ Joinを独立して使用できます。 統合されたデータセットを取得したら、IronPDFを活用して統合データに基づくPDFドキュメントを動的に生成できます。

以下は簡略化された例です：

// Assume 'customerOrderInfo' is a result set obtained using LINQ Join
var pdfDocument = new IronPdf.ChromePdfRenderer();
foreach (var entry in customerOrderInfo)
{
    // Use IronPDF to add content to the PDF based on integrated data
    pdfDocument.AddHTML($"<p>Customer ID: {entry.CustomerID}, Order ID: {entry.OrderID}</p>");
}
// Save or render the PDF document as needed
pdfDocument.SaveAs("IntegratedDataDocument.pdf");

// Assume 'customerOrderInfo' is a result set obtained using LINQ Join
var pdfDocument = new IronPdf.ChromePdfRenderer();
foreach (var entry in customerOrderInfo)
{
    // Use IronPDF to add content to the PDF based on integrated data
    pdfDocument.AddHTML($"<p>Customer ID: {entry.CustomerID}, Order ID: {entry.OrderID}</p>");
}
// Save or render the PDF document as needed
pdfDocument.SaveAs("IntegratedDataDocument.pdf");

' Assume 'customerOrderInfo' is a result set obtained using LINQ Join
Dim pdfDocument = New IronPdf.ChromePdfRenderer()
For Each entry In customerOrderInfo
	' Use IronPDF to add content to the PDF based on integrated data
	pdfDocument.AddHTML($"<p>Customer ID: {entry.CustomerID}, Order ID: {entry.OrderID}</p>")
Next entry
' Save or render the PDF document as needed
pdfDocument.SaveAs("IntegratedDataDocument.pdf")

PDFドキュメント生成のより多くの方法と、LINQ JoinをIronPDFと共に使用する方法について、IronPDFドキュメンテーションをご覧ください。

シナリオ2：PDF生成中の動的データ統合

IronPDFは、PDFドキュメントに動的なコンテンツを追加することができ、PDF生成プロセス自体でLINQ Joinを使用したデータ統合が可能です。 ここでは、顧客クラスを作成し、現実のアプリケーションを表現するために注文を行います。 データソースはSQLデータベースや構造化フォーマットであることができ、この場合、データ属性のセットを含むオブジェクトリストはデータベースのテーブルのようなものです。 以下の例は、IronPDFを使用したLINQ Joinメソッドの詳細な統合を、HTML文字列によるPDF生成にて文書作成することで示しています：

using System;
using System.Collections.Generic;
using System.Linq;
using IronPdf;

class Order
{
    public int OrderID { get; set; }
    public int CustomerID { get; set; }
    // Other order-related properties...
}

class Customer
{
    public int CustomerID { get; set; }
    // Other customer-related properties...
}

class Program
{
    static void Main()
    {
        // Sample orders collection
        var orders = new List<Order>
        {
            new Order { OrderID = 1, CustomerID = 1 },
            new Order { OrderID = 2, CustomerID = 1 },
            new Order { OrderID = 3, CustomerID = 2 },
        };

        // Sample customers collection
        var customers = new List<Customer>
        {
            new Customer { CustomerID = 1 },
            new Customer { CustomerID = 2 },
        };

        var pdfDocument = new ChromePdfRenderer();
        string htmlContent = "<h1>Details generated using LINQ JOIN</h1>";

        // Use join to find customer orders
        var query = from customer in customers
                    join order in orders on customer.CustomerID equals order.CustomerID
                    select new { CustomerID = customer.CustomerID, OrderID = order.OrderID };

        foreach (var result in query)
        {
            // Use IronPDF to dynamically add content to the PDF based on integrated data
            htmlContent += $"<p>Customer ID: {result.CustomerID}, Order ID: {result.OrderID}</p>";
        }

        // Save or render the PDF document as needed
        pdfDocument.RenderHtmlAsPdf(htmlContent)
                   .SaveAs("DynamicIntegratedDataDocument.pdf");
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using IronPdf;

class Order
{
    public int OrderID { get; set; }
    public int CustomerID { get; set; }
    // Other order-related properties...
}

class Customer
{
    public int CustomerID { get; set; }
    // Other customer-related properties...
}

class Program
{
    static void Main()
    {
        // Sample orders collection
        var orders = new List<Order>
        {
            new Order { OrderID = 1, CustomerID = 1 },
            new Order { OrderID = 2, CustomerID = 1 },
            new Order { OrderID = 3, CustomerID = 2 },
        };

        // Sample customers collection
        var customers = new List<Customer>
        {
            new Customer { CustomerID = 1 },
            new Customer { CustomerID = 2 },
        };

        var pdfDocument = new ChromePdfRenderer();
        string htmlContent = "<h1>Details generated using LINQ JOIN</h1>";

        // Use join to find customer orders
        var query = from customer in customers
                    join order in orders on customer.CustomerID equals order.CustomerID
                    select new { CustomerID = customer.CustomerID, OrderID = order.OrderID };

        foreach (var result in query)
        {
            // Use IronPDF to dynamically add content to the PDF based on integrated data
            htmlContent += $"<p>Customer ID: {result.CustomerID}, Order ID: {result.OrderID}</p>";
        }

        // Save or render the PDF document as needed
        pdfDocument.RenderHtmlAsPdf(htmlContent)
                   .SaveAs("DynamicIntegratedDataDocument.pdf");
    }
}

Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports IronPdf

Friend Class Order
	Public Property OrderID() As Integer
	Public Property CustomerID() As Integer
	' Other order-related properties...
End Class

Friend Class Customer
	Public Property CustomerID() As Integer
	' Other customer-related properties...
End Class

Friend Class Program
	Shared Sub Main()
		' Sample orders collection
		Dim orders = New List(Of Order) From {
			New Order With {
				.OrderID = 1,
				.CustomerID = 1
			},
			New Order With {
				.OrderID = 2,
				.CustomerID = 1
			},
			New Order With {
				.OrderID = 3,
				.CustomerID = 2
			}
		}

		' Sample customers collection
		Dim customers = New List(Of Customer) From {
			New Customer With {.CustomerID = 1},
			New Customer With {.CustomerID = 2}
		}

		Dim pdfDocument = New ChromePdfRenderer()
		Dim htmlContent As String = "<h1>Details generated using LINQ JOIN</h1>"

		' Use join to find customer orders
		Dim query = From customer In customers
			Join order In orders On customer.CustomerID Equals order.CustomerID
			Select New With {
				Key .CustomerID = customer.CustomerID,
				Key .OrderID = order.OrderID
			}

		For Each result In query
			' Use IronPDF to dynamically add content to the PDF based on integrated data
			htmlContent &= $"<p>Customer ID: {result.CustomerID}, Order ID: {result.OrderID}</p>"
		Next result

		' Save or render the PDF document as needed
		pdfDocument.RenderHtmlAsPdf(htmlContent).SaveAs("DynamicIntegratedDataDocument.pdf")
	End Sub
End Class

このコードは、顧客ごとの一致する注文を見つけるのに役立つjoinキーワードを活用し、クエリをより簡潔で表現の豊かなものにします。