DataSet.MergeFailed 事件

定义

命名空间:

System.Data

程序集:

System.Data.Common.dll

Source:

DataSet.cs

当目标和源 DataRow 的主键值相同且 EnforceConstraints 设置为真时发生。

public:
 event System::Data::MergeFailedEventHandler ^ MergeFailed;

public event System.Data.MergeFailedEventHandler? MergeFailed;

member this.MergeFailed : System.Data.MergeFailedEventHandler 

Public Custom Event MergeFailed As MergeFailedEventHandler 

事件类型

MergeFailedEventHandler

示例

下面的示例演示如何使用 MergeFailed 事件。

private static void DemonstrateMergeFailedEvent()
{
    // Create a DataSet with one table containing two columns.
    DataSet dataSet = new DataSet("dataSet");
    DataTable table = new DataTable("Items");

    // Add table to the DataSet.
    dataSet.Tables.Add(table);

    // Add two columns to the DataTable.
    table.Columns.Add("id", typeof(int));
    table.Columns.Add("item", typeof(int));

    // Set the primary key to the first column.
    table.PrimaryKey = new DataColumn[] { table.Columns["id"] };

    // Add MergeFailed event handler for the table.
    dataSet.MergeFailed += new MergeFailedEventHandler(Merge_Failed);

    // Create a second DataTable identical to the first,
    DataTable t2 = table.Clone();

    // Set the primary key of the new table to the second column.
    // This will cause the MergeFailed event to be raised when the
    // table is merged into the DataSet.
    t2.PrimaryKey = new DataColumn[] { t2.Columns["item"] };

    // Merge the table into the DataSet.
    Console.WriteLine("Merging...");
    dataSet.Merge(t2, false, MissingSchemaAction.Add);
}

private static void Merge_Failed(object sender, MergeFailedEventArgs e)
{
    Console.WriteLine("Merge_Failed Event: '{0}'", e.Conflict);
}

Private Shared Sub DemonstrateMergeFailedEvent()
    ' Create a DataSet with one table containing two columns.
    Dim dataSet As New DataSet("dataSet")
    Dim table As New DataTable("Items")
    
    ' Add table to the DataSet.
    dataSet.Tables.Add(table)

    ' Add two columns to the DataTable.
    table.Columns.Add("id", Type.GetType("System.Int32"))
    table.Columns.Add("item", Type.GetType("System.Int32"))

    ' Set the primary key to the first column.
    table.PrimaryKey = new DataColumn() { table.Columns("id") }

    ' Add MergeFailed event handler for the table.
    AddHandler dataSet.MergeFailed, _
        New MergeFailedEventHandler(AddressOf Merge_Failed)

    ' Create a second DataTable identical to the first, 
    Dim t2 As DataTable = table.Clone()

    ' Set the primary key of the new table to the second column.
    ' This will cause the MergeFailed event to be raised when the
    ' table is merged into the DataSet.
    t2.PrimaryKey = New DataColumn() { t2.Columns("item") }
    
    ' Merge table into the DataSet.
    Console.WriteLine("Merging...")
    dataSet.Merge(t2, false, MissingSchemaAction.Add)
End Sub

Private Shared Sub Merge_Failed(sender As object, _
    e As MergeFailedEventArgs)
    Console.WriteLine("Merge_Failed Event: '{0}'", e.Conflict)
End Sub

注解

有关如何处理事件的详细信息，请参阅 处理和引发事件。

另请参阅

• 在 ADO.NET 中使用数据集