Rockford .Net User Group

This example is based on an example from Introducing Microsoft LINQ. I modified it to work with VS 2008 Beta 2.

First, I created a Customer class that mapped to some of the fields in the database:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Linq.Mapping;

namespace LinqToSql1
{
    [System.Data.Linq.Mapping.Table(Name="Customers")]
    class Customer
    {
        [Column(Name="Customer ID")]
        public string CustomerID;
        [Column(Name="Company Name")]
        public string CompanyName;
        [Column]
        public string City;
        [Column(Name = "Region")]
        public string State;
        [Column]
        public string Country;
    }
}

Then I wrote the main part of the program, which looks for customers from the state of Washington.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Linq;

namespace LinqToSql1
{
    class Program
    {
        static void Main(string[] args)
        {
         DataContext db = new System.Data.Linq.DataContext("Northwind.sdf");
         Table<Customer> Customers = db.GetTable<Customer>();
         string SQLCommand = "DELETE FROM Customers WHERE City='Seattle'";

            var query =
                from c in Customers
                where c.Country == "USA" && c.State == "WA"
                select new { c.CustomerID, c.CompanyName, c.City };

            foreach (var row in query)
            {
                Console.WriteLine(row);
            }
        }
    }
}
Running this code produced the following:

{ CustomerID = LAZYK, CompanyName = Lazy K Kountry Store, City = Walla Walla }
{ CustomerID = TRAIH, CompanyName = Trail's Head Gourmet Provisioners, City = Ki
rkland }
{ CustomerID = WHITC, CompanyName = White Clover Markets, City = Seattle }
Press any key to continue . . .

The SQL string is from an attempt to simulate a SQL insertion. When I placed it in my "where" clause, the "query" variable wasn't created and the foreach didn't execute. I even hard-coded that string in quotes and it ran safely. When I tried:

it didn't even compile. LINQ doesn't recognize "DELETE", "INSERT", or "UPDATE" as commands, but rather as normal strings. Later, I might demonstrate how LINQ performs the equivalent of those SQL commands. One last thing: I used a version of the Northwind database as you might have guessed.

Ross Albertson