How to use the ADO.NET MergeFailed event

This article mainly explains how to use ADO. NET MergeFailed event. Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let's let Xiaobian take you to learn how to use ADO. NET MergeFailed event.

We all know that the DataSet object provides three events: Disposed, Initialized, and MergeFailed. Here we will only describe ADO. NET MergeFailed events in detail.

ADO. NET MergeFailed event

The most common event for DataSet objects is MergeFailed, which is raised when the schema of the DataSet objects to be merged conflicts. This occurs when the target and source DataRows have the same primary key value and the EnforceConstraints property is set to true. For example, if the primary key columns of the merged table are the same as those of the tables in both DataSet objects, an exception occurs and a MergeFailed event is raised. The MergeFailedEventArgs object passed to the MergeFailed event has a Conflict attribute, which identifies the schema conflict between the two DataSet objects, and a Table attribute, which identifies the name of the conflicting table.

The following code snippet demonstrates how to add an event handler for an ADO. NET MergeFailed event.

AddHandler workDS.MergeFailed, New MergeFailedEventHandler( _ AddressOf DataSetMergeFailed) Private Shared Sub DataSetMergeFailed(_ sender As Object,args As MergeFailedEventArgs) Console.WriteLine("Merge failed for table " & args.Table.TableName) Console.WriteLine("Conflict = " & args.Conflict) End Sub

Initialize ADO. NET MergeFailed event

The Initialized event occurs after the DataSet constructor initializes a new instance of the DataSet.

The IsInitialized property returns true if the DataSet has completed initialization; otherwise, false. The BeginInit method, which starts initializing the DataSet, sets IsInitialized to false. The EndInit method, which ends the initialization of the DataSet, sets it to true. The Visual Studio design environment uses these methods to initialize DataSets used by other components. These methods are not usually used in code.

release event

DataSet derives from the MarshalByValueComponent class, which exposes the Dispose method and the Disposed event. The Disposed event adds an event handler to listen for disposed events on the component. If you want to execute code when you call the Dispose method, you can use the Disposed event of the DataSet. Dispose Frees resources used by MarshalByValueComponent.

DataSet and DataTable objects inherit MarshalByValueComponent and support the ISerializable interface for remoting. These two objects are *** Remotable ADO. NET objects.

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