如何:检测到并解决冲突的提交How to: Detect and Resolve Conflicting Submissions

LINQ to SQLLINQ to SQL 提供了许多资源,用于检测和解决因多个用户更改数据库而产生的冲突。provides many resources for detecting and resolving conflicts that stem from multi-user changes to the database. 有关详细信息,请参阅如何:管理更改冲突For more information, see How to: Manage Change Conflicts.

示例Example

try下面的示例演示/ catch捕获异常的块。ChangeConflictExceptionThe following example shows a try/catch block that catches a ChangeConflictException exception. 每个冲突的实体和成员信息会显示在控制台窗口中。Entity and member information for each conflict is displayed in the console window.

备注

您必须将 using System.Reflection 指令(在 Visual Basic 中为 Imports System.Reflection)包含在内,以支持信息检索。You must include the using System.Reflection directive (Imports System.Reflection in Visual Basic) to support the information retrieval. 有关详细信息,请参阅 System.ReflectionFor more information, see System.Reflection.

// using System.Reflection;
Northwnd db = new Northwnd(@"c:\northwnd.mdf");

Customer newCust = new Customer();
newCust.City = "Auburn";
newCust.CustomerID = "AUBUR";
newCust.CompanyName = "AubCo";
db.Customers.InsertOnSubmit(newCust);

try
{
    db.SubmitChanges(ConflictMode.ContinueOnConflict);
}
catch (ChangeConflictException e)
{
    Console.WriteLine("Optimistic concurrency error.");
    Console.WriteLine(e.Message);
    Console.ReadLine();
    foreach (ObjectChangeConflict occ in db.ChangeConflicts)
    {
        MetaTable metatable = db.Mapping.GetTable(occ.Object.GetType());
        Customer entityInConflict = (Customer)occ.Object;
        Console.WriteLine("Table name: {0}", metatable.TableName);
        Console.Write("Customer ID: ");
        Console.WriteLine(entityInConflict.CustomerID);
        foreach (MemberChangeConflict mcc in occ.MemberConflicts)
        {
            object currVal = mcc.CurrentValue;
            object origVal = mcc.OriginalValue;
            object databaseVal = mcc.DatabaseValue;
            MemberInfo mi = mcc.Member;
            Console.WriteLine("Member: {0}", mi.Name);
            Console.WriteLine("current value: {0}", currVal);
            Console.WriteLine("original value: {0}", origVal);
            Console.WriteLine("database value: {0}", databaseVal);
        }
    }
}
catch (Exception ee)
{
    // Catch other exceptions.
    Console.WriteLine(ee.Message);
}
finally
{
    Console.WriteLine("TryCatch block has finished.");
}
' Imports System.Reflection

Dim newCust As New Customer()
newCust.City = "Auburn"
newCust.CustomerID = "AUBUR"
newCust.CompanyName = "AubCo"
db.Customers.InsertOnSubmit(newCust)

Try
    db.SubmitChanges(ConflictMode.ContinueOnConflict)

Catch e As ChangeConflictException
    Console.WriteLine("Optimistic concurrency error.")
    Console.WriteLine(e.Message)
    Console.ReadLine()
    For Each occ In db.ChangeConflicts

        Dim metatable As MetaTable = db.Mapping.GetTable(occ.Object.GetType())
        Dim entityInConflict = CType(occ.Object, Customer)
        Console.WriteLine("Table name: {0}", metatable.TableName)
        Console.Write("Customer ID: ")
        Console.WriteLine(entityInConflict.CustomerID)
        For Each mcc In occ.MemberConflicts

            Dim currVal = mcc.CurrentValue
            Dim origVal = mcc.OriginalValue
            Dim databaseVal = mcc.DatabaseValue
            Dim mi = mcc.Member
            Console.WriteLine("Member: {0}", mi.Name)
            Console.WriteLine("current value: {0}", currVal)
            Console.WriteLine("original value: {0}", origVal)
            Console.WriteLine("database value: {0}", databaseVal)
        Next
    Next

Catch ee As Exception
    ' Catch other exceptions.
    Console.WriteLine(ee.Message)
Finally
    Console.WriteLine("TryCatch block has finished.")
End Try

请参阅See also