Select method of DataTable is used to select rows from datatable (see this post). We can have multiple Boolean conditions in select method just like we do in SQL. It some situations it can save many round trips to database.
DataRow[] SelectedRow= MyDataTable.Select("Id = 5 Or RegistrationNo=72);
Yawer Iqbal 
DataTable.Select(“(ID,NAME) in (5,’Girish’)”);
is it possible?
Select() method has 4 overloads. The one that accepts 2 arguments (both arguments are string type) take first argument as filter expression and second as sort expression.
You can use this but what I see is your way is not correct. Please see http://msdn.microsoft.com/en-us/library/way3dy9w.aspx for code example of correctly using it.