When you want to run a query and show the subset of data in a control, a DataView could help you. That's just one example, look at the MSDN example for DataView, that explains where you should use DataViews with DataTables...
DataTable
A datatable is an in-memory representation of a single database table. You can think of it as having columns and rows in the same way. The DataTable is a central object in the ADO.NET library. Other objects that use the DataTable include the DataSet and the DataView.
Look at MSDN The DataTable class for more details.
DataView
A dataview is a view on a datatable, a bit like a sql view. It allows you to filter and sort the rows - often for binding to a windows form control.
Additionally, a DataView can be customized to present a subset of data from the DataTable. This capability allows you to have two controls bound to the same DataTable, but showing different versions of the data. For example, one control may be bound to a DataView showing all of the rows in the table, while a second may be configured to display only the rows that have been deleted from the DataTable. The DataTable also has a DefaultView property which returns the default DataView for the table.
Look at MSDN DataView class for more details.
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