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DataSet.MergeFailed Event

Occurs when a target and source DataRow have the same primary key value, and EnforceConstraints is set to true.

Namespace:  System.Data
Assembly:  System.Data (in System.Data.dll)

'Declaration
Public Event MergeFailed As MergeFailedEventHandler

For more information about handling events, see Consuming Events.

The following example demonstrates the use of the MergeFailed event.

Private Shared Sub DemonstrateMergeFailedEvent()
	' Create a DataSet with one table containing two columns. 
	Dim dataSet AS DataSet = New DataSet("dataSet")
	Dim table As DataTable = 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

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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