Gets a copy of the System.Data.DataSet that contains all changes made to it since it was loaded or since DataSet.AcceptChanges was last called.
A copy of the changes from this System.Data.DataSet that can have actions performed on it and later be merged back in using DataSet.Merge(DataSet). If no changed rows are found, the method returns null.
Creates a new System.Data.DataSet that contains a copy of all rows in the original System.Data.DataSet that have pending changes. Relationship constraints can cause additional unchanged rows to be added to the new System.Data.DataSet if the unchanged rows contain primary keys corresponding to foreign keys in the changed rows. The method returns null if there are no rows in the original System.Data.DataSet that have pending changes.