u can use DataTable Select method to perform this
DataRow[] dr = DataSet1.Tables[0].Select ("Name Like '%ab'");
or u can use DataView.
DataView dv = DataSet1.Tables[0].DefaultView;
dv.RowFilter = "Name Like '%ab%'";
A%a is not allowed in filter expressions. Check MSDN for more details. What you can do is set the filter expression like this
"Name Like 'A%' AND Name Like '%a'"
Try this hopefully this will work.