This delegate represents the method that will handle the DataSet.MergeFailed event. This event occurs if you invoke DataSet.Merge( ) to combine two DataSet objects where source and target rows have a different primary key. Note that this event occurs only if DataSet.EnforceConstraints is set to true , and it doesn't occur if the schemas are invalid (in which case an exception is thrown before the merge process is started). When a merge fails, the DataSet.EnforceConstraints property is set to false , all the data is retained, and the rows that are invalid are marked with a descriptive DataRow.RowError . You can't reenable constraint checking until these conflicts are resolved.
public delegate void MergeFailedEventHandler (object sender , MergeFailedEventArgs e );