如何顯示變更集

您可以使用 GetChangeSet來檢視 DataContext 追蹤的變更。

範例

下列範例會擷取城市為倫敦的客戶、將城市變更為巴黎，並將變更提交回資料庫。

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($"CustomerID: {custObj.CustomerID}");
    Console.WriteLine($"\tOriginal value: {custObj.City}");
    custObj.City = "Paris";
    Console.WriteLine($"\tUpdated value: {custObj.City}");
}

ChangeSet cs = db.GetChangeSet();
Console.Write("Total changes: {0}", cs);
// Freeze the console window.
Console.ReadLine();

db.SubmitChanges();

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()

此程式代碼的輸出如下所示。 請注意，結尾的摘要顯示已進行八項變更。

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}

另請參閱

• 偵錯支援