Csharp/CSharp Tutorial/LINQ/DataSet

LINQ to DataSet

<source lang="csharp">using System; using System.Collections.Generic; using System.Linq; using System.Data; using System.Data.SqlClient; using System.Data.Linq; using System.Data.rumon; using System.Text;

   class Program
   {
       static void Main(string[] args)
       {
           SqlConnection thisConnection = new SqlConnection(
               @"Data Source=.\SQLEXPRESS;" +
               @"AttachDbFilename="NORTHWND.MDF";" +
               @"Integrated Security=True;Connect Timeout=30;User Instance=true");
           SqlDataAdapter thisAdapter = new SqlDataAdapter("SELECT CustomerID, CompanyName FROM Customers", thisConnection);
           SqlCommandBuilder thisBuilder = new SqlCommandBuilder(thisAdapter);
           DataSet thisDataSet = new DataSet();
           SqlDataAdapter custAdapter = new SqlDataAdapter("SELECT * FROM Customers", thisConnection);
           SqlDataAdapter orderAdapter = new SqlDataAdapter("SELECT * FROM Orders", thisConnection);
           custAdapter.Fill(thisDataSet, "Customers");
           orderAdapter.Fill(thisDataSet, "Orders");
           DataRelation custOrderRel = thisDataSet.Relations.Add("CustOrders",
                thisDataSet.Tables["Customers"].Columns["CustomerID"],
                thisDataSet.Tables["Orders"].Columns["CustomerID"]);
           var customers = thisDataSet.Tables["Customers"].AsEnumerable();
           var orders = thisDataSet.Tables["Orders"].AsEnumerable();
           var preferredCustomers = from c in customers
               where c.GetChildRows("CustOrders").Length > 10
               select c;
           foreach (var customer in preferredCustomers)
           {
               Console.WriteLine(customer.GetChildRows("CustOrders").Length);
               Console.WriteLine(customer["CustomerID"]);
           }
           thisConnection.Close();
       }
   }</source>

Linq To Sql

<source lang="csharp">using System; using System.Linq; using System.Data.Linq; using System.Data.Linq.Mapping;

   [Table]
   public class Customers
   {
       [Column]
       public string customerId;
       [Column]
       public string companyName;
       [Column]
       public string city;
       [Column]
       public string country;
   }
   class LinqToSql
   {
       static void Main(string[] args)
       {
           string connString = @"server = .\sqlexpress;integrated security = true;database = northwind";
           DataContext db = new DataContext(connString);
           Table<Customers> customers = db.GetTable<Customers>();
           var custs = from c in customers where c.country == "USA" orderby c.city select c;
           foreach (var c in custs)
               Console.WriteLine(
                  "{0}, {1}, {2}, {3}",
                  c.customerId,
                  c.rupanyName,
                  c.city,
                  c.country
               );
       }
   }</source>

Simple Linq to SQL

<source lang="csharp">using System; using System.Data.Linq; using System.Data.Linq.Mapping; using System.Linq;

   [Table(Name="Sales.Customer")]
   public class Customer
   {
       [Column] public string FirstName    { get; set; }
       [Column] public string LastName     { get; set; }
       [Column] public string EmailAddress { get; set; }
       public override string ToString()
       {
           return string.Format("{0} {1}\nEmail:   {2}",FirstName, LastName, EmailAddress);
       }
   }
   public class Tester
   {
       static void Main()
       {
           DataContext db = new DataContext(@"Data Source=.\SqlExpress;Initial Catalog=AdventureWorks;Integrated Security=True");
           Table<Customer> customers = db.GetTable<Customer>();
           var query = from customer in customers where customer.FirstName == "D" select customer;
           foreach(var c in query)
               Console.WriteLine(c.ToString());
       }
   }</source>