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Query Expression Syntax Examples: Element Operators

  • Artikkeli

The examples in this topic demonstrate how to use the First method to query the AdventureWorks Sales Model using the query expression syntax. The AdventureWorks Sales Model used in these examples is built from the Contact, Address, Product, SalesOrderHeader, and SalesOrderDetail tables in the AdventureWorks sample database.

The examples in this topic use the following using/Imports statements:

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

First

Example

The following example uses the First method to return the first contact whose first name is "Brooke".

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

    Contact query = (
        from contact in contacts
        where contact.FirstName == firstName
        select contact)
        .First();

    Console.WriteLine("ContactID: " + query.ContactID);
    Console.WriteLine("FirstName: " + query.FirstName);
    Console.WriteLine("LastName: " + query.LastName);
}

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

    Dim query As Contact = ( _
        From cont In contacts _
        Where cont.FirstName = firstName _
        Select cont).First()

    Console.WriteLine("ContactID: " & query.ContactID)
    Console.WriteLine("FirstName: " & query.FirstName)
    Console.WriteLine("LastName: " & query.LastName)
End Using

See also