Cómo: Mostrar un conjunto de cambios (LINQ to SQL)
Actualización: November 2007
Puede ver los cambios de los que DataContext ha realizado un seguimiento mediante GetChangeSet.
Ejemplo
En el ejemplo siguiente se recuperan los clientes cuya ciudad es Londres, se cambia la ciudad a París y se envían los cambios a la base de datos.
Dim db As New Northwnd("c:\northwnd.mdf")
Dim custQuery = _
From cust In db.Customers _
Where (cust.City = "London") _
Select cust
For Each custObj As Customer In custQuery
Console.WriteLine("CustomerID: {0}", custObj.CustomerID)
Console.WriteLine(vbTab & "Original value: {0}", custObj.City)
custObj.City = "Paris"
Console.WriteLine(vbTab & "Updated value: {0}", custObj.City)
Next
Dim cs As ChangeSet = db.GetChangeSet()
Console.Write("Total changes: {0}", cs)
' Freeze the console window.
Console.ReadLine()
db.SubmitChanges()
Northwnd db = new Northwnd(@"c:\northwnd.mdf");
var custQuery =
from cust in db.Customers
where cust.City == "London"
select cust;
foreach (Customer custObj in custQuery)
{
Console.WriteLine("CustomerID: {0}", custObj.CustomerID);
Console.WriteLine("\tOriginal value: {0}", custObj.City);
custObj.City = "Paris";
Console.WriteLine("\tUpdated value: {0}", custObj.City);
}
ChangeSet cs = db.GetChangeSet();
Console.Write("Total changes: {0}", cs);
// Freeze the console window.
Console.ReadLine();
db.SubmitChanges();
El resultado de este código es similar al siguiente. Observe que el resumen final indica que se realizaron ocho cambios.
CustomerID: AROUT
Original value: London
Updated value: Paris
CustomerID: BSBEV
Original value: London
Updated value: Paris
CustomerID: CONSH
Original value: London
Updated value: Paris
CustomerID: EASTC
Original value: London
Updated value: Paris
CustomerID: NORTS
Original value: London
Updated value: Paris
CustomerID: PARIS
Original value: London
Updated value: Paris
CustomerID: SEVES
Original value: London
Updated value: Paris
CustomerID: SPECD
Original value: London
Updated value: Paris
Total changes: {Added: 0, Removed: 0, Modified: 8}