如何：显示变更集 (LINQ to SQL)
可以通过使用 GetChangeSet 来查看由 DataContext 跟踪的更改。
示例
下面的示例检索所在城市为伦敦的客户，将其所在城市更改为巴黎，然后将所做的更改提交回数据库。
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();
执行此代码所得到的输出与如下内容类似。 请注意，结尾处的摘要显示做了八项更改。
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}